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-rw-r--r--drivers/md/dm-vdo/block-map.c3318
1 files changed, 3318 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/block-map.c b/drivers/md/dm-vdo/block-map.c
new file mode 100644
index 0000000000..a0a7c1bd63
--- /dev/null
+++ b/drivers/md/dm-vdo/block-map.c
@@ -0,0 +1,3318 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "block-map.h"
+
+#include <linux/bio.h>
+#include <linux/ratelimit.h>
+
+#include "errors.h"
+#include "logger.h"
+#include "memory-alloc.h"
+#include "permassert.h"
+
+#include "action-manager.h"
+#include "admin-state.h"
+#include "completion.h"
+#include "constants.h"
+#include "data-vio.h"
+#include "encodings.h"
+#include "io-submitter.h"
+#include "physical-zone.h"
+#include "recovery-journal.h"
+#include "slab-depot.h"
+#include "status-codes.h"
+#include "types.h"
+#include "vdo.h"
+#include "vio.h"
+#include "wait-queue.h"
+
+/**
+ * DOC: Block map eras
+ *
+ * The block map era, or maximum age, is used as follows:
+ *
+ * Each block map page, when dirty, records the earliest recovery journal block sequence number of
+ * the changes reflected in that dirty block. Sequence numbers are classified into eras: every
+ * @maximum_age sequence numbers, we switch to a new era. Block map pages are assigned to eras
+ * according to the sequence number they record.
+ *
+ * In the current (newest) era, block map pages are not written unless there is cache pressure. In
+ * the next oldest era, each time a new journal block is written 1/@maximum_age of the pages in
+ * this era are issued for write. In all older eras, pages are issued for write immediately.
+ */
+
+struct page_descriptor {
+ root_count_t root_index;
+ height_t height;
+ page_number_t page_index;
+ slot_number_t slot;
+} __packed;
+
+union page_key {
+ struct page_descriptor descriptor;
+ u64 key;
+};
+
+struct write_if_not_dirtied_context {
+ struct block_map_zone *zone;
+ u8 generation;
+};
+
+struct block_map_tree_segment {
+ struct tree_page *levels[VDO_BLOCK_MAP_TREE_HEIGHT];
+};
+
+struct block_map_tree {
+ struct block_map_tree_segment *segments;
+};
+
+struct forest {
+ struct block_map *map;
+ size_t segments;
+ struct boundary *boundaries;
+ struct tree_page **pages;
+ struct block_map_tree trees[];
+};
+
+struct cursor_level {
+ page_number_t page_index;
+ slot_number_t slot;
+};
+
+struct cursors;
+
+struct cursor {
+ struct vdo_waiter waiter;
+ struct block_map_tree *tree;
+ height_t height;
+ struct cursors *parent;
+ struct boundary boundary;
+ struct cursor_level levels[VDO_BLOCK_MAP_TREE_HEIGHT];
+ struct pooled_vio *vio;
+};
+
+struct cursors {
+ struct block_map_zone *zone;
+ struct vio_pool *pool;
+ vdo_entry_callback_fn entry_callback;
+ struct vdo_completion *completion;
+ root_count_t active_roots;
+ struct cursor cursors[];
+};
+
+static const physical_block_number_t NO_PAGE = 0xFFFFFFFFFFFFFFFF;
+
+/* Used to indicate that the page holding the location of a tree root has been "loaded". */
+static const physical_block_number_t VDO_INVALID_PBN = 0xFFFFFFFFFFFFFFFF;
+
+const struct block_map_entry UNMAPPED_BLOCK_MAP_ENTRY = {
+ .mapping_state = VDO_MAPPING_STATE_UNMAPPED & 0x0F,
+ .pbn_high_nibble = 0,
+ .pbn_low_word = __cpu_to_le32(VDO_ZERO_BLOCK & UINT_MAX),
+};
+
+#define LOG_INTERVAL 4000
+#define DISPLAY_INTERVAL 100000
+
+/*
+ * For adjusting VDO page cache statistic fields which are only mutated on the logical zone thread.
+ * Prevents any compiler shenanigans from affecting other threads reading those stats.
+ */
+#define ADD_ONCE(value, delta) WRITE_ONCE(value, (value) + (delta))
+
+static inline bool is_dirty(const struct page_info *info)
+{
+ return info->state == PS_DIRTY;
+}
+
+static inline bool is_present(const struct page_info *info)
+{
+ return (info->state == PS_RESIDENT) || (info->state == PS_DIRTY);
+}
+
+static inline bool is_in_flight(const struct page_info *info)
+{
+ return (info->state == PS_INCOMING) || (info->state == PS_OUTGOING);
+}
+
+static inline bool is_incoming(const struct page_info *info)
+{
+ return info->state == PS_INCOMING;
+}
+
+static inline bool is_outgoing(const struct page_info *info)
+{
+ return info->state == PS_OUTGOING;
+}
+
+static inline bool is_valid(const struct page_info *info)
+{
+ return is_present(info) || is_outgoing(info);
+}
+
+static char *get_page_buffer(struct page_info *info)
+{
+ struct vdo_page_cache *cache = info->cache;
+
+ return &cache->pages[(info - cache->infos) * VDO_BLOCK_SIZE];
+}
+
+static inline struct vdo_page_completion *page_completion_from_waiter(struct vdo_waiter *waiter)
+{
+ struct vdo_page_completion *completion;
+
+ if (waiter == NULL)
+ return NULL;
+
+ completion = container_of(waiter, struct vdo_page_completion, waiter);
+ vdo_assert_completion_type(&completion->completion, VDO_PAGE_COMPLETION);
+ return completion;
+}
+
+/**
+ * initialize_info() - Initialize all page info structures and put them on the free list.
+ *
+ * Return: VDO_SUCCESS or an error.
+ */
+static int initialize_info(struct vdo_page_cache *cache)
+{
+ struct page_info *info;
+
+ INIT_LIST_HEAD(&cache->free_list);
+ for (info = cache->infos; info < cache->infos + cache->page_count; info++) {
+ int result;
+
+ info->cache = cache;
+ info->state = PS_FREE;
+ info->pbn = NO_PAGE;
+
+ result = create_metadata_vio(cache->vdo, VIO_TYPE_BLOCK_MAP,
+ VIO_PRIORITY_METADATA, info,
+ get_page_buffer(info), &info->vio);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ /* The thread ID should never change. */
+ info->vio->completion.callback_thread_id = cache->zone->thread_id;
+
+ INIT_LIST_HEAD(&info->state_entry);
+ list_add_tail(&info->state_entry, &cache->free_list);
+ INIT_LIST_HEAD(&info->lru_entry);
+ }
+
+ return VDO_SUCCESS;
+}
+
+/**
+ * allocate_cache_components() - Allocate components of the cache which require their own
+ * allocation.
+ * @maximum_age: The number of journal blocks before a dirtied page is considered old and must be
+ * written out.
+ *
+ * The caller is responsible for all clean up on errors.
+ *
+ * Return: VDO_SUCCESS or an error code.
+ */
+static int __must_check allocate_cache_components(struct vdo_page_cache *cache)
+{
+ u64 size = cache->page_count * (u64) VDO_BLOCK_SIZE;
+ int result;
+
+ result = vdo_allocate(cache->page_count, struct page_info, "page infos",
+ &cache->infos);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = vdo_allocate_memory(size, VDO_BLOCK_SIZE, "cache pages", &cache->pages);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = vdo_int_map_create(cache->page_count, &cache->page_map);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ return initialize_info(cache);
+}
+
+/**
+ * assert_on_cache_thread() - Assert that a function has been called on the VDO page cache's
+ * thread.
+ */
+static inline void assert_on_cache_thread(struct vdo_page_cache *cache,
+ const char *function_name)
+{
+ thread_id_t thread_id = vdo_get_callback_thread_id();
+
+ VDO_ASSERT_LOG_ONLY((thread_id == cache->zone->thread_id),
+ "%s() must only be called on cache thread %d, not thread %d",
+ function_name, cache->zone->thread_id, thread_id);
+}
+
+/** assert_io_allowed() - Assert that a page cache may issue I/O. */
+static inline void assert_io_allowed(struct vdo_page_cache *cache)
+{
+ VDO_ASSERT_LOG_ONLY(!vdo_is_state_quiescent(&cache->zone->state),
+ "VDO page cache may issue I/O");
+}
+
+/** report_cache_pressure() - Log and, if enabled, report cache pressure. */
+static void report_cache_pressure(struct vdo_page_cache *cache)
+{
+ ADD_ONCE(cache->stats.cache_pressure, 1);
+ if (cache->waiter_count > cache->page_count) {
+ if ((cache->pressure_report % LOG_INTERVAL) == 0)
+ vdo_log_info("page cache pressure %u", cache->stats.cache_pressure);
+
+ if (++cache->pressure_report >= DISPLAY_INTERVAL)
+ cache->pressure_report = 0;
+ }
+}
+
+/**
+ * get_page_state_name() - Return the name of a page state.
+ *
+ * If the page state is invalid a static string is returned and the invalid state is logged.
+ *
+ * Return: A pointer to a static page state name.
+ */
+static const char * __must_check get_page_state_name(enum vdo_page_buffer_state state)
+{
+ int result;
+ static const char * const state_names[] = {
+ "FREE", "INCOMING", "FAILED", "RESIDENT", "DIRTY", "OUTGOING"
+ };
+
+ BUILD_BUG_ON(ARRAY_SIZE(state_names) != PAGE_STATE_COUNT);
+
+ result = VDO_ASSERT(state < ARRAY_SIZE(state_names),
+ "Unknown page_state value %d", state);
+ if (result != VDO_SUCCESS)
+ return "[UNKNOWN PAGE STATE]";
+
+ return state_names[state];
+}
+
+/**
+ * update_counter() - Update the counter associated with a given state.
+ * @info: The page info to count.
+ * @delta: The delta to apply to the counter.
+ */
+static void update_counter(struct page_info *info, s32 delta)
+{
+ struct block_map_statistics *stats = &info->cache->stats;
+
+ switch (info->state) {
+ case PS_FREE:
+ ADD_ONCE(stats->free_pages, delta);
+ return;
+
+ case PS_INCOMING:
+ ADD_ONCE(stats->incoming_pages, delta);
+ return;
+
+ case PS_OUTGOING:
+ ADD_ONCE(stats->outgoing_pages, delta);
+ return;
+
+ case PS_FAILED:
+ ADD_ONCE(stats->failed_pages, delta);
+ return;
+
+ case PS_RESIDENT:
+ ADD_ONCE(stats->clean_pages, delta);
+ return;
+
+ case PS_DIRTY:
+ ADD_ONCE(stats->dirty_pages, delta);
+ return;
+
+ default:
+ return;
+ }
+}
+
+/** update_lru() - Update the lru information for an active page. */
+static void update_lru(struct page_info *info)
+{
+ if (info->cache->lru_list.prev != &info->lru_entry)
+ list_move_tail(&info->lru_entry, &info->cache->lru_list);
+}
+
+/**
+ * set_info_state() - Set the state of a page_info and put it on the right list, adjusting
+ * counters.
+ */
+static void set_info_state(struct page_info *info, enum vdo_page_buffer_state new_state)
+{
+ if (new_state == info->state)
+ return;
+
+ update_counter(info, -1);
+ info->state = new_state;
+ update_counter(info, 1);
+
+ switch (info->state) {
+ case PS_FREE:
+ case PS_FAILED:
+ list_move_tail(&info->state_entry, &info->cache->free_list);
+ return;
+
+ case PS_OUTGOING:
+ list_move_tail(&info->state_entry, &info->cache->outgoing_list);
+ return;
+
+ case PS_DIRTY:
+ return;
+
+ default:
+ list_del_init(&info->state_entry);
+ }
+}
+
+/** set_info_pbn() - Set the pbn for an info, updating the map as needed. */
+static int __must_check set_info_pbn(struct page_info *info, physical_block_number_t pbn)
+{
+ struct vdo_page_cache *cache = info->cache;
+
+ /* Either the new or the old page number must be NO_PAGE. */
+ int result = VDO_ASSERT((pbn == NO_PAGE) || (info->pbn == NO_PAGE),
+ "Must free a page before reusing it.");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ if (info->pbn != NO_PAGE)
+ vdo_int_map_remove(cache->page_map, info->pbn);
+
+ info->pbn = pbn;
+
+ if (pbn != NO_PAGE) {
+ result = vdo_int_map_put(cache->page_map, pbn, info, true, NULL);
+ if (result != VDO_SUCCESS)
+ return result;
+ }
+ return VDO_SUCCESS;
+}
+
+/** reset_page_info() - Reset page info to represent an unallocated page. */
+static int reset_page_info(struct page_info *info)
+{
+ int result;
+
+ result = VDO_ASSERT(info->busy == 0, "VDO Page must not be busy");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = VDO_ASSERT(!vdo_waitq_has_waiters(&info->waiting),
+ "VDO Page must not have waiters");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = set_info_pbn(info, NO_PAGE);
+ set_info_state(info, PS_FREE);
+ list_del_init(&info->lru_entry);
+ return result;
+}
+
+/**
+ * find_free_page() - Find a free page.
+ *
+ * Return: A pointer to the page info structure (if found), NULL otherwise.
+ */
+static struct page_info * __must_check find_free_page(struct vdo_page_cache *cache)
+{
+ struct page_info *info;
+
+ info = list_first_entry_or_null(&cache->free_list, struct page_info,
+ state_entry);
+ if (info != NULL)
+ list_del_init(&info->state_entry);
+
+ return info;
+}
+
+/**
+ * find_page() - Find the page info (if any) associated with a given pbn.
+ * @pbn: The absolute physical block number of the page.
+ *
+ * Return: The page info for the page if available, or NULL if not.
+ */
+static struct page_info * __must_check find_page(struct vdo_page_cache *cache,
+ physical_block_number_t pbn)
+{
+ if ((cache->last_found != NULL) && (cache->last_found->pbn == pbn))
+ return cache->last_found;
+
+ cache->last_found = vdo_int_map_get(cache->page_map, pbn);
+ return cache->last_found;
+}
+
+/**
+ * select_lru_page() - Determine which page is least recently used.
+ *
+ * Picks the least recently used from among the non-busy entries at the front of each of the lru
+ * ring. Since whenever we mark a page busy we also put it to the end of the ring it is unlikely
+ * that the entries at the front are busy unless the queue is very short, but not impossible.
+ *
+ * Return: A pointer to the info structure for a relevant page, or NULL if no such page can be
+ * found. The page can be dirty or resident.
+ */
+static struct page_info * __must_check select_lru_page(struct vdo_page_cache *cache)
+{
+ struct page_info *info;
+
+ list_for_each_entry(info, &cache->lru_list, lru_entry)
+ if ((info->busy == 0) && !is_in_flight(info))
+ return info;
+
+ return NULL;
+}
+
+/* ASYNCHRONOUS INTERFACE BEYOND THIS POINT */
+
+/**
+ * complete_with_page() - Helper to complete the VDO Page Completion request successfully.
+ * @info: The page info representing the result page.
+ * @vdo_page_comp: The VDO page completion to complete.
+ */
+static void complete_with_page(struct page_info *info,
+ struct vdo_page_completion *vdo_page_comp)
+{
+ bool available = vdo_page_comp->writable ? is_present(info) : is_valid(info);
+
+ if (!available) {
+ vdo_log_error_strerror(VDO_BAD_PAGE,
+ "Requested cache page %llu in state %s is not %s",
+ (unsigned long long) info->pbn,
+ get_page_state_name(info->state),
+ vdo_page_comp->writable ? "present" : "valid");
+ vdo_fail_completion(&vdo_page_comp->completion, VDO_BAD_PAGE);
+ return;
+ }
+
+ vdo_page_comp->info = info;
+ vdo_page_comp->ready = true;
+ vdo_finish_completion(&vdo_page_comp->completion);
+}
+
+/**
+ * complete_waiter_with_error() - Complete a page completion with an error code.
+ * @waiter: The page completion, as a waiter.
+ * @result_ptr: A pointer to the error code.
+ *
+ * Implements waiter_callback_fn.
+ */
+static void complete_waiter_with_error(struct vdo_waiter *waiter, void *result_ptr)
+{
+ int *result = result_ptr;
+
+ vdo_fail_completion(&page_completion_from_waiter(waiter)->completion, *result);
+}
+
+/**
+ * complete_waiter_with_page() - Complete a page completion with a page.
+ * @waiter: The page completion, as a waiter.
+ * @page_info: The page info to complete with.
+ *
+ * Implements waiter_callback_fn.
+ */
+static void complete_waiter_with_page(struct vdo_waiter *waiter, void *page_info)
+{
+ complete_with_page(page_info, page_completion_from_waiter(waiter));
+}
+
+/**
+ * distribute_page_over_waitq() - Complete a waitq of VDO page completions with a page result.
+ *
+ * Upon completion the waitq will be empty.
+ *
+ * Return: The number of pages distributed.
+ */
+static unsigned int distribute_page_over_waitq(struct page_info *info,
+ struct vdo_wait_queue *waitq)
+{
+ size_t num_pages;
+
+ update_lru(info);
+ num_pages = vdo_waitq_num_waiters(waitq);
+
+ /*
+ * Increment the busy count once for each pending completion so that this page does not
+ * stop being busy until all completions have been processed.
+ */
+ info->busy += num_pages;
+
+ vdo_waitq_notify_all_waiters(waitq, complete_waiter_with_page, info);
+ return num_pages;
+}
+
+/**
+ * set_persistent_error() - Set a persistent error which all requests will receive in the future.
+ * @context: A string describing what triggered the error.
+ *
+ * Once triggered, all enqueued completions will get this error. Any future requests will result in
+ * this error as well.
+ */
+static void set_persistent_error(struct vdo_page_cache *cache, const char *context,
+ int result)
+{
+ struct page_info *info;
+ /* If we're already read-only, there's no need to log. */
+ struct vdo *vdo = cache->vdo;
+
+ if ((result != VDO_READ_ONLY) && !vdo_is_read_only(vdo)) {
+ vdo_log_error_strerror(result, "VDO Page Cache persistent error: %s",
+ context);
+ vdo_enter_read_only_mode(vdo, result);
+ }
+
+ assert_on_cache_thread(cache, __func__);
+
+ vdo_waitq_notify_all_waiters(&cache->free_waiters,
+ complete_waiter_with_error, &result);
+ cache->waiter_count = 0;
+
+ for (info = cache->infos; info < cache->infos + cache->page_count; info++) {
+ vdo_waitq_notify_all_waiters(&info->waiting,
+ complete_waiter_with_error, &result);
+ }
+}
+
+/**
+ * validate_completed_page() - Check that a page completion which is being freed to the cache
+ * referred to a valid page and is in a valid state.
+ * @writable: Whether a writable page is required.
+ *
+ * Return: VDO_SUCCESS if the page was valid, otherwise as error
+ */
+static int __must_check validate_completed_page(struct vdo_page_completion *completion,
+ bool writable)
+{
+ int result;
+
+ result = VDO_ASSERT(completion->ready, "VDO Page completion not ready");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = VDO_ASSERT(completion->info != NULL,
+ "VDO Page Completion must be complete");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = VDO_ASSERT(completion->info->pbn == completion->pbn,
+ "VDO Page Completion pbn must be consistent");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = VDO_ASSERT(is_valid(completion->info),
+ "VDO Page Completion page must be valid");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ if (writable) {
+ result = VDO_ASSERT(completion->writable,
+ "VDO Page Completion must be writable");
+ if (result != VDO_SUCCESS)
+ return result;
+ }
+
+ return VDO_SUCCESS;
+}
+
+static void check_for_drain_complete(struct block_map_zone *zone)
+{
+ if (vdo_is_state_draining(&zone->state) &&
+ (zone->active_lookups == 0) &&
+ !vdo_waitq_has_waiters(&zone->flush_waiters) &&
+ !is_vio_pool_busy(zone->vio_pool) &&
+ (zone->page_cache.outstanding_reads == 0) &&
+ (zone->page_cache.outstanding_writes == 0)) {
+ vdo_finish_draining_with_result(&zone->state,
+ (vdo_is_read_only(zone->block_map->vdo) ?
+ VDO_READ_ONLY : VDO_SUCCESS));
+ }
+}
+
+static void enter_zone_read_only_mode(struct block_map_zone *zone, int result)
+{
+ vdo_enter_read_only_mode(zone->block_map->vdo, result);
+
+ /*
+ * We are in read-only mode, so we won't ever write any page out.
+ * Just take all waiters off the waitq so the zone can drain.
+ */
+ vdo_waitq_init(&zone->flush_waiters);
+ check_for_drain_complete(zone);
+}
+
+static bool __must_check
+validate_completed_page_or_enter_read_only_mode(struct vdo_page_completion *completion,
+ bool writable)
+{
+ int result = validate_completed_page(completion, writable);
+
+ if (result == VDO_SUCCESS)
+ return true;
+
+ enter_zone_read_only_mode(completion->info->cache->zone, result);
+ return false;
+}
+
+/**
+ * handle_load_error() - Handle page load errors.
+ * @completion: The page read vio.
+ */
+static void handle_load_error(struct vdo_completion *completion)
+{
+ int result = completion->result;
+ struct page_info *info = completion->parent;
+ struct vdo_page_cache *cache = info->cache;
+
+ assert_on_cache_thread(cache, __func__);
+ vio_record_metadata_io_error(as_vio(completion));
+ vdo_enter_read_only_mode(cache->zone->block_map->vdo, result);
+ ADD_ONCE(cache->stats.failed_reads, 1);
+ set_info_state(info, PS_FAILED);
+ vdo_waitq_notify_all_waiters(&info->waiting, complete_waiter_with_error, &result);
+ reset_page_info(info);
+
+ /*
+ * Don't decrement until right before calling check_for_drain_complete() to
+ * ensure that the above work can't cause the page cache to be freed out from under us.
+ */
+ cache->outstanding_reads--;
+ check_for_drain_complete(cache->zone);
+}
+
+/**
+ * page_is_loaded() - Callback used when a page has been loaded.
+ * @completion: The vio which has loaded the page. Its parent is the page_info.
+ */
+static void page_is_loaded(struct vdo_completion *completion)
+{
+ struct page_info *info = completion->parent;
+ struct vdo_page_cache *cache = info->cache;
+ nonce_t nonce = info->cache->zone->block_map->nonce;
+ struct block_map_page *page;
+ enum block_map_page_validity validity;
+
+ assert_on_cache_thread(cache, __func__);
+
+ page = (struct block_map_page *) get_page_buffer(info);
+ validity = vdo_validate_block_map_page(page, nonce, info->pbn);
+ if (validity == VDO_BLOCK_MAP_PAGE_BAD) {
+ physical_block_number_t pbn = vdo_get_block_map_page_pbn(page);
+ int result = vdo_log_error_strerror(VDO_BAD_PAGE,
+ "Expected page %llu but got page %llu instead",
+ (unsigned long long) info->pbn,
+ (unsigned long long) pbn);
+
+ vdo_continue_completion(completion, result);
+ return;
+ }
+
+ if (validity == VDO_BLOCK_MAP_PAGE_INVALID)
+ vdo_format_block_map_page(page, nonce, info->pbn, false);
+
+ info->recovery_lock = 0;
+ set_info_state(info, PS_RESIDENT);
+ distribute_page_over_waitq(info, &info->waiting);
+
+ /*
+ * Don't decrement until right before calling check_for_drain_complete() to
+ * ensure that the above work can't cause the page cache to be freed out from under us.
+ */
+ cache->outstanding_reads--;
+ check_for_drain_complete(cache->zone);
+}
+
+/**
+ * handle_rebuild_read_error() - Handle a read error during a read-only rebuild.
+ * @completion: The page load completion.
+ */
+static void handle_rebuild_read_error(struct vdo_completion *completion)
+{
+ struct page_info *info = completion->parent;
+ struct vdo_page_cache *cache = info->cache;
+
+ assert_on_cache_thread(cache, __func__);
+
+ /*
+ * We are doing a read-only rebuild, so treat this as a successful read
+ * of an uninitialized page.
+ */
+ vio_record_metadata_io_error(as_vio(completion));
+ ADD_ONCE(cache->stats.failed_reads, 1);
+ memset(get_page_buffer(info), 0, VDO_BLOCK_SIZE);
+ vdo_reset_completion(completion);
+ page_is_loaded(completion);
+}
+
+static void load_cache_page_endio(struct bio *bio)
+{
+ struct vio *vio = bio->bi_private;
+ struct page_info *info = vio->completion.parent;
+
+ continue_vio_after_io(vio, page_is_loaded, info->cache->zone->thread_id);
+}
+
+/**
+ * launch_page_load() - Begin the process of loading a page.
+ *
+ * Return: VDO_SUCCESS or an error code.
+ */
+static int __must_check launch_page_load(struct page_info *info,
+ physical_block_number_t pbn)
+{
+ int result;
+ vdo_action_fn callback;
+ struct vdo_page_cache *cache = info->cache;
+
+ assert_io_allowed(cache);
+
+ result = set_info_pbn(info, pbn);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = VDO_ASSERT((info->busy == 0), "Page is not busy before loading.");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ set_info_state(info, PS_INCOMING);
+ cache->outstanding_reads++;
+ ADD_ONCE(cache->stats.pages_loaded, 1);
+ callback = (cache->rebuilding ? handle_rebuild_read_error : handle_load_error);
+ vdo_submit_metadata_vio(info->vio, pbn, load_cache_page_endio,
+ callback, REQ_OP_READ | REQ_PRIO);
+ return VDO_SUCCESS;
+}
+
+static void write_pages(struct vdo_completion *completion);
+
+/** handle_flush_error() - Handle errors flushing the layer. */
+static void handle_flush_error(struct vdo_completion *completion)
+{
+ struct page_info *info = completion->parent;
+
+ vio_record_metadata_io_error(as_vio(completion));
+ set_persistent_error(info->cache, "flush failed", completion->result);
+ write_pages(completion);
+}
+
+static void flush_endio(struct bio *bio)
+{
+ struct vio *vio = bio->bi_private;
+ struct page_info *info = vio->completion.parent;
+
+ continue_vio_after_io(vio, write_pages, info->cache->zone->thread_id);
+}
+
+/** save_pages() - Attempt to save the outgoing pages by first flushing the layer. */
+static void save_pages(struct vdo_page_cache *cache)
+{
+ struct page_info *info;
+ struct vio *vio;
+
+ if ((cache->pages_in_flush > 0) || (cache->pages_to_flush == 0))
+ return;
+
+ assert_io_allowed(cache);
+
+ info = list_first_entry(&cache->outgoing_list, struct page_info, state_entry);
+
+ cache->pages_in_flush = cache->pages_to_flush;
+ cache->pages_to_flush = 0;
+ ADD_ONCE(cache->stats.flush_count, 1);
+
+ vio = info->vio;
+
+ /*
+ * We must make sure that the recovery journal entries that changed these pages were
+ * successfully persisted, and thus must issue a flush before each batch of pages is
+ * written to ensure this.
+ */
+ vdo_submit_flush_vio(vio, flush_endio, handle_flush_error);
+}
+
+/**
+ * schedule_page_save() - Add a page to the outgoing list of pages waiting to be saved.
+ *
+ * Once in the list, a page may not be used until it has been written out.
+ */
+static void schedule_page_save(struct page_info *info)
+{
+ if (info->busy > 0) {
+ info->write_status = WRITE_STATUS_DEFERRED;
+ return;
+ }
+
+ info->cache->pages_to_flush++;
+ info->cache->outstanding_writes++;
+ set_info_state(info, PS_OUTGOING);
+}
+
+/**
+ * launch_page_save() - Add a page to outgoing pages waiting to be saved, and then start saving
+ * pages if another save is not in progress.
+ */
+static void launch_page_save(struct page_info *info)
+{
+ schedule_page_save(info);
+ save_pages(info->cache);
+}
+
+/**
+ * completion_needs_page() - Determine whether a given vdo_page_completion (as a waiter) is
+ * requesting a given page number.
+ * @context: A pointer to the pbn of the desired page.
+ *
+ * Implements waiter_match_fn.
+ *
+ * Return: true if the page completion is for the desired page number.
+ */
+static bool completion_needs_page(struct vdo_waiter *waiter, void *context)
+{
+ physical_block_number_t *pbn = context;
+
+ return (page_completion_from_waiter(waiter)->pbn == *pbn);
+}
+
+/**
+ * allocate_free_page() - Allocate a free page to the first completion in the waiting queue, and
+ * any other completions that match it in page number.
+ */
+static void allocate_free_page(struct page_info *info)
+{
+ int result;
+ struct vdo_waiter *oldest_waiter;
+ physical_block_number_t pbn;
+ struct vdo_page_cache *cache = info->cache;
+
+ assert_on_cache_thread(cache, __func__);
+
+ if (!vdo_waitq_has_waiters(&cache->free_waiters)) {
+ if (cache->stats.cache_pressure > 0) {
+ vdo_log_info("page cache pressure relieved");
+ WRITE_ONCE(cache->stats.cache_pressure, 0);
+ }
+
+ return;
+ }
+
+ result = reset_page_info(info);
+ if (result != VDO_SUCCESS) {
+ set_persistent_error(cache, "cannot reset page info", result);
+ return;
+ }
+
+ oldest_waiter = vdo_waitq_get_first_waiter(&cache->free_waiters);
+ pbn = page_completion_from_waiter(oldest_waiter)->pbn;
+
+ /*
+ * Remove all entries which match the page number in question and push them onto the page
+ * info's waitq.
+ */
+ vdo_waitq_dequeue_matching_waiters(&cache->free_waiters, completion_needs_page,
+ &pbn, &info->waiting);
+ cache->waiter_count -= vdo_waitq_num_waiters(&info->waiting);
+
+ result = launch_page_load(info, pbn);
+ if (result != VDO_SUCCESS) {
+ vdo_waitq_notify_all_waiters(&info->waiting,
+ complete_waiter_with_error, &result);
+ }
+}
+
+/**
+ * discard_a_page() - Begin the process of discarding a page.
+ *
+ * If no page is discardable, increments a count of deferred frees so that the next release of a
+ * page which is no longer busy will kick off another discard cycle. This is an indication that the
+ * cache is not big enough.
+ *
+ * If the selected page is not dirty, immediately allocates the page to the oldest completion
+ * waiting for a free page.
+ */
+static void discard_a_page(struct vdo_page_cache *cache)
+{
+ struct page_info *info = select_lru_page(cache);
+
+ if (info == NULL) {
+ report_cache_pressure(cache);
+ return;
+ }
+
+ if (!is_dirty(info)) {
+ allocate_free_page(info);
+ return;
+ }
+
+ VDO_ASSERT_LOG_ONLY(!is_in_flight(info),
+ "page selected for discard is not in flight");
+
+ cache->discard_count++;
+ info->write_status = WRITE_STATUS_DISCARD;
+ launch_page_save(info);
+}
+
+/**
+ * discard_page_for_completion() - Helper used to trigger a discard so that the completion can get
+ * a different page.
+ */
+static void discard_page_for_completion(struct vdo_page_completion *vdo_page_comp)
+{
+ struct vdo_page_cache *cache = vdo_page_comp->cache;
+
+ cache->waiter_count++;
+ vdo_waitq_enqueue_waiter(&cache->free_waiters, &vdo_page_comp->waiter);
+ discard_a_page(cache);
+}
+
+/**
+ * discard_page_if_needed() - Helper used to trigger a discard if the cache needs another free
+ * page.
+ * @cache: The page cache.
+ */
+static void discard_page_if_needed(struct vdo_page_cache *cache)
+{
+ if (cache->waiter_count > cache->discard_count)
+ discard_a_page(cache);
+}
+
+/**
+ * write_has_finished() - Inform the cache that a write has finished (possibly with an error).
+ * @info: The info structure for the page whose write just completed.
+ *
+ * Return: true if the page write was a discard.
+ */
+static bool write_has_finished(struct page_info *info)
+{
+ bool was_discard = (info->write_status == WRITE_STATUS_DISCARD);
+
+ assert_on_cache_thread(info->cache, __func__);
+ info->cache->outstanding_writes--;
+
+ info->write_status = WRITE_STATUS_NORMAL;
+ return was_discard;
+}
+
+/**
+ * handle_page_write_error() - Handler for page write errors.
+ * @completion: The page write vio.
+ */
+static void handle_page_write_error(struct vdo_completion *completion)
+{
+ int result = completion->result;
+ struct page_info *info = completion->parent;
+ struct vdo_page_cache *cache = info->cache;
+
+ vio_record_metadata_io_error(as_vio(completion));
+
+ /* If we're already read-only, write failures are to be expected. */
+ if (result != VDO_READ_ONLY) {
+ vdo_log_ratelimit(vdo_log_error,
+ "failed to write block map page %llu",
+ (unsigned long long) info->pbn);
+ }
+
+ set_info_state(info, PS_DIRTY);
+ ADD_ONCE(cache->stats.failed_writes, 1);
+ set_persistent_error(cache, "cannot write page", result);
+
+ if (!write_has_finished(info))
+ discard_page_if_needed(cache);
+
+ check_for_drain_complete(cache->zone);
+}
+
+static void page_is_written_out(struct vdo_completion *completion);
+
+static void write_cache_page_endio(struct bio *bio)
+{
+ struct vio *vio = bio->bi_private;
+ struct page_info *info = vio->completion.parent;
+
+ continue_vio_after_io(vio, page_is_written_out, info->cache->zone->thread_id);
+}
+
+/**
+ * page_is_written_out() - Callback used when a page has been written out.
+ * @completion: The vio which wrote the page. Its parent is a page_info.
+ */
+static void page_is_written_out(struct vdo_completion *completion)
+{
+ bool was_discard, reclaimed;
+ u32 reclamations;
+ struct page_info *info = completion->parent;
+ struct vdo_page_cache *cache = info->cache;
+ struct block_map_page *page = (struct block_map_page *) get_page_buffer(info);
+
+ if (!page->header.initialized) {
+ page->header.initialized = true;
+ vdo_submit_metadata_vio(info->vio, info->pbn,
+ write_cache_page_endio,
+ handle_page_write_error,
+ REQ_OP_WRITE | REQ_PRIO | REQ_PREFLUSH);
+ return;
+ }
+
+ /* Handle journal updates and torn write protection. */
+ vdo_release_recovery_journal_block_reference(cache->zone->block_map->journal,
+ info->recovery_lock,
+ VDO_ZONE_TYPE_LOGICAL,
+ cache->zone->zone_number);
+ info->recovery_lock = 0;
+ was_discard = write_has_finished(info);
+ reclaimed = (!was_discard || (info->busy > 0) || vdo_waitq_has_waiters(&info->waiting));
+
+ set_info_state(info, PS_RESIDENT);
+
+ reclamations = distribute_page_over_waitq(info, &info->waiting);
+ ADD_ONCE(cache->stats.reclaimed, reclamations);
+
+ if (was_discard)
+ cache->discard_count--;
+
+ if (reclaimed)
+ discard_page_if_needed(cache);
+ else
+ allocate_free_page(info);
+
+ check_for_drain_complete(cache->zone);
+}
+
+/**
+ * write_pages() - Write the batch of pages which were covered by the layer flush which just
+ * completed.
+ * @flush_completion: The flush vio.
+ *
+ * This callback is registered in save_pages().
+ */
+static void write_pages(struct vdo_completion *flush_completion)
+{
+ struct vdo_page_cache *cache = ((struct page_info *) flush_completion->parent)->cache;
+
+ /*
+ * We need to cache these two values on the stack since it is possible for the last
+ * page info to cause the page cache to get freed. Hence once we launch the last page,
+ * it may be unsafe to dereference the cache.
+ */
+ bool has_unflushed_pages = (cache->pages_to_flush > 0);
+ page_count_t pages_in_flush = cache->pages_in_flush;
+
+ cache->pages_in_flush = 0;
+ while (pages_in_flush-- > 0) {
+ struct page_info *info =
+ list_first_entry(&cache->outgoing_list, struct page_info,
+ state_entry);
+
+ list_del_init(&info->state_entry);
+ if (vdo_is_read_only(info->cache->vdo)) {
+ struct vdo_completion *completion = &info->vio->completion;
+
+ vdo_reset_completion(completion);
+ completion->callback = page_is_written_out;
+ completion->error_handler = handle_page_write_error;
+ vdo_fail_completion(completion, VDO_READ_ONLY);
+ continue;
+ }
+ ADD_ONCE(info->cache->stats.pages_saved, 1);
+ vdo_submit_metadata_vio(info->vio, info->pbn, write_cache_page_endio,
+ handle_page_write_error, REQ_OP_WRITE | REQ_PRIO);
+ }
+
+ if (has_unflushed_pages) {
+ /*
+ * If there are unflushed pages, the cache can't have been freed, so this call is
+ * safe.
+ */
+ save_pages(cache);
+ }
+}
+
+/**
+ * vdo_release_page_completion() - Release a VDO Page Completion.
+ *
+ * The page referenced by this completion (if any) will no longer be held busy by this completion.
+ * If a page becomes discardable and there are completions awaiting free pages then a new round of
+ * page discarding is started.
+ */
+void vdo_release_page_completion(struct vdo_completion *completion)
+{
+ struct page_info *discard_info = NULL;
+ struct vdo_page_completion *page_completion = as_vdo_page_completion(completion);
+ struct vdo_page_cache *cache;
+
+ if (completion->result == VDO_SUCCESS) {
+ if (!validate_completed_page_or_enter_read_only_mode(page_completion, false))
+ return;
+
+ if (--page_completion->info->busy == 0)
+ discard_info = page_completion->info;
+ }
+
+ VDO_ASSERT_LOG_ONLY((page_completion->waiter.next_waiter == NULL),
+ "Page being released after leaving all queues");
+
+ page_completion->info = NULL;
+ cache = page_completion->cache;
+ assert_on_cache_thread(cache, __func__);
+
+ if (discard_info != NULL) {
+ if (discard_info->write_status == WRITE_STATUS_DEFERRED) {
+ discard_info->write_status = WRITE_STATUS_NORMAL;
+ launch_page_save(discard_info);
+ }
+
+ /*
+ * if there are excess requests for pages (that have not already started discards)
+ * we need to discard some page (which may be this one)
+ */
+ discard_page_if_needed(cache);
+ }
+}
+
+/**
+ * load_page_for_completion() - Helper function to load a page as described by a VDO Page
+ * Completion.
+ */
+static void load_page_for_completion(struct page_info *info,
+ struct vdo_page_completion *vdo_page_comp)
+{
+ int result;
+
+ vdo_waitq_enqueue_waiter(&info->waiting, &vdo_page_comp->waiter);
+ result = launch_page_load(info, vdo_page_comp->pbn);
+ if (result != VDO_SUCCESS) {
+ vdo_waitq_notify_all_waiters(&info->waiting,
+ complete_waiter_with_error, &result);
+ }
+}
+
+/**
+ * vdo_get_page() - Initialize a page completion and get a block map page.
+ * @page_completion: The vdo_page_completion to initialize.
+ * @zone: The block map zone of the desired page.
+ * @pbn: The absolute physical block of the desired page.
+ * @writable: Whether the page can be modified.
+ * @parent: The object to notify when the fetch is complete.
+ * @callback: The notification callback.
+ * @error_handler: The handler for fetch errors.
+ * @requeue: Whether we must requeue when notifying the parent.
+ *
+ * May cause another page to be discarded (potentially writing a dirty page) and the one nominated
+ * by the completion to be loaded from disk. When the callback is invoked, the page will be
+ * resident in the cache and marked busy. All callers must call vdo_release_page_completion()
+ * when they are done with the page to clear the busy mark.
+ */
+void vdo_get_page(struct vdo_page_completion *page_completion,
+ struct block_map_zone *zone, physical_block_number_t pbn,
+ bool writable, void *parent, vdo_action_fn callback,
+ vdo_action_fn error_handler, bool requeue)
+{
+ struct vdo_page_cache *cache = &zone->page_cache;
+ struct vdo_completion *completion = &page_completion->completion;
+ struct page_info *info;
+
+ assert_on_cache_thread(cache, __func__);
+ VDO_ASSERT_LOG_ONLY((page_completion->waiter.next_waiter == NULL),
+ "New page completion was not already on a wait queue");
+
+ *page_completion = (struct vdo_page_completion) {
+ .pbn = pbn,
+ .writable = writable,
+ .cache = cache,
+ };
+
+ vdo_initialize_completion(completion, cache->vdo, VDO_PAGE_COMPLETION);
+ vdo_prepare_completion(completion, callback, error_handler,
+ cache->zone->thread_id, parent);
+ completion->requeue = requeue;
+
+ if (page_completion->writable && vdo_is_read_only(cache->vdo)) {
+ vdo_fail_completion(completion, VDO_READ_ONLY);
+ return;
+ }
+
+ if (page_completion->writable)
+ ADD_ONCE(cache->stats.write_count, 1);
+ else
+ ADD_ONCE(cache->stats.read_count, 1);
+
+ info = find_page(cache, page_completion->pbn);
+ if (info != NULL) {
+ /* The page is in the cache already. */
+ if ((info->write_status == WRITE_STATUS_DEFERRED) ||
+ is_incoming(info) ||
+ (is_outgoing(info) && page_completion->writable)) {
+ /* The page is unusable until it has finished I/O. */
+ ADD_ONCE(cache->stats.wait_for_page, 1);
+ vdo_waitq_enqueue_waiter(&info->waiting, &page_completion->waiter);
+ return;
+ }
+
+ if (is_valid(info)) {
+ /* The page is usable. */
+ ADD_ONCE(cache->stats.found_in_cache, 1);
+ if (!is_present(info))
+ ADD_ONCE(cache->stats.read_outgoing, 1);
+ update_lru(info);
+ info->busy++;
+ complete_with_page(info, page_completion);
+ return;
+ }
+
+ /* Something horrible has gone wrong. */
+ VDO_ASSERT_LOG_ONLY(false, "Info found in a usable state.");
+ }
+
+ /* The page must be fetched. */
+ info = find_free_page(cache);
+ if (info != NULL) {
+ ADD_ONCE(cache->stats.fetch_required, 1);
+ load_page_for_completion(info, page_completion);
+ return;
+ }
+
+ /* The page must wait for a page to be discarded. */
+ ADD_ONCE(cache->stats.discard_required, 1);
+ discard_page_for_completion(page_completion);
+}
+
+/**
+ * vdo_request_page_write() - Request that a VDO page be written out as soon as it is not busy.
+ * @completion: The vdo_page_completion containing the page.
+ */
+void vdo_request_page_write(struct vdo_completion *completion)
+{
+ struct page_info *info;
+ struct vdo_page_completion *vdo_page_comp = as_vdo_page_completion(completion);
+
+ if (!validate_completed_page_or_enter_read_only_mode(vdo_page_comp, true))
+ return;
+
+ info = vdo_page_comp->info;
+ set_info_state(info, PS_DIRTY);
+ launch_page_save(info);
+}
+
+/**
+ * vdo_get_cached_page() - Get the block map page from a page completion.
+ * @completion: A vdo page completion whose callback has been called.
+ * @page_ptr: A pointer to hold the page
+ *
+ * Return: VDO_SUCCESS or an error
+ */
+int vdo_get_cached_page(struct vdo_completion *completion,
+ struct block_map_page **page_ptr)
+{
+ int result;
+ struct vdo_page_completion *vpc;
+
+ vpc = as_vdo_page_completion(completion);
+ result = validate_completed_page(vpc, true);
+ if (result == VDO_SUCCESS)
+ *page_ptr = (struct block_map_page *) get_page_buffer(vpc->info);
+
+ return result;
+}
+
+/**
+ * vdo_invalidate_page_cache() - Invalidate all entries in the VDO page cache.
+ *
+ * There must not be any dirty pages in the cache.
+ *
+ * Return: A success or error code.
+ */
+int vdo_invalidate_page_cache(struct vdo_page_cache *cache)
+{
+ struct page_info *info;
+
+ assert_on_cache_thread(cache, __func__);
+
+ /* Make sure we don't throw away any dirty pages. */
+ for (info = cache->infos; info < cache->infos + cache->page_count; info++) {
+ int result = VDO_ASSERT(!is_dirty(info), "cache must have no dirty pages");
+
+ if (result != VDO_SUCCESS)
+ return result;
+ }
+
+ /* Reset the page map by re-allocating it. */
+ vdo_int_map_free(vdo_forget(cache->page_map));
+ return vdo_int_map_create(cache->page_count, &cache->page_map);
+}
+
+/**
+ * get_tree_page_by_index() - Get the tree page for a given height and page index.
+ *
+ * Return: The requested page.
+ */
+static struct tree_page * __must_check get_tree_page_by_index(struct forest *forest,
+ root_count_t root_index,
+ height_t height,
+ page_number_t page_index)
+{
+ page_number_t offset = 0;
+ size_t segment;
+
+ for (segment = 0; segment < forest->segments; segment++) {
+ page_number_t border = forest->boundaries[segment].levels[height - 1];
+
+ if (page_index < border) {
+ struct block_map_tree *tree = &forest->trees[root_index];
+
+ return &(tree->segments[segment].levels[height - 1][page_index - offset]);
+ }
+
+ offset = border;
+ }
+
+ return NULL;
+}
+
+/* Get the page referred to by the lock's tree slot at its current height. */
+static inline struct tree_page *get_tree_page(const struct block_map_zone *zone,
+ const struct tree_lock *lock)
+{
+ return get_tree_page_by_index(zone->block_map->forest, lock->root_index,
+ lock->height,
+ lock->tree_slots[lock->height].page_index);
+}
+
+/** vdo_copy_valid_page() - Validate and copy a buffer to a page. */
+bool vdo_copy_valid_page(char *buffer, nonce_t nonce,
+ physical_block_number_t pbn,
+ struct block_map_page *page)
+{
+ struct block_map_page *loaded = (struct block_map_page *) buffer;
+ enum block_map_page_validity validity =
+ vdo_validate_block_map_page(loaded, nonce, pbn);
+
+ if (validity == VDO_BLOCK_MAP_PAGE_VALID) {
+ memcpy(page, loaded, VDO_BLOCK_SIZE);
+ return true;
+ }
+
+ if (validity == VDO_BLOCK_MAP_PAGE_BAD) {
+ vdo_log_error_strerror(VDO_BAD_PAGE,
+ "Expected page %llu but got page %llu instead",
+ (unsigned long long) pbn,
+ (unsigned long long) vdo_get_block_map_page_pbn(loaded));
+ }
+
+ return false;
+}
+
+/**
+ * in_cyclic_range() - Check whether the given value is between the lower and upper bounds, within
+ * a cyclic range of values from 0 to (modulus - 1).
+ * @lower: The lowest value to accept.
+ * @value: The value to check.
+ * @upper: The highest value to accept.
+ * @modulus: The size of the cyclic space, no more than 2^15.
+ *
+ * The value and both bounds must be smaller than the modulus.
+ *
+ * Return: true if the value is in range.
+ */
+static bool in_cyclic_range(u16 lower, u16 value, u16 upper, u16 modulus)
+{
+ if (value < lower)
+ value += modulus;
+ if (upper < lower)
+ upper += modulus;
+ return (value <= upper);
+}
+
+/**
+ * is_not_older() - Check whether a generation is strictly older than some other generation in the
+ * context of a zone's current generation range.
+ * @zone: The zone in which to do the comparison.
+ * @a: The generation in question.
+ * @b: The generation to compare to.
+ *
+ * Return: true if generation @a is not strictly older than generation @b in the context of @zone
+ */
+static bool __must_check is_not_older(struct block_map_zone *zone, u8 a, u8 b)
+{
+ int result;
+
+ result = VDO_ASSERT((in_cyclic_range(zone->oldest_generation, a, zone->generation, 1 << 8) &&
+ in_cyclic_range(zone->oldest_generation, b, zone->generation, 1 << 8)),
+ "generation(s) %u, %u are out of range [%u, %u]",
+ a, b, zone->oldest_generation, zone->generation);
+ if (result != VDO_SUCCESS) {
+ enter_zone_read_only_mode(zone, result);
+ return true;
+ }
+
+ return in_cyclic_range(b, a, zone->generation, 1 << 8);
+}
+
+static void release_generation(struct block_map_zone *zone, u8 generation)
+{
+ int result;
+
+ result = VDO_ASSERT((zone->dirty_page_counts[generation] > 0),
+ "dirty page count underflow for generation %u", generation);
+ if (result != VDO_SUCCESS) {
+ enter_zone_read_only_mode(zone, result);
+ return;
+ }
+
+ zone->dirty_page_counts[generation]--;
+ while ((zone->dirty_page_counts[zone->oldest_generation] == 0) &&
+ (zone->oldest_generation != zone->generation))
+ zone->oldest_generation++;
+}
+
+static void set_generation(struct block_map_zone *zone, struct tree_page *page,
+ u8 new_generation)
+{
+ u32 new_count;
+ int result;
+ bool decrement_old = vdo_waiter_is_waiting(&page->waiter);
+ u8 old_generation = page->generation;
+
+ if (decrement_old && (old_generation == new_generation))
+ return;
+
+ page->generation = new_generation;
+ new_count = ++zone->dirty_page_counts[new_generation];
+ result = VDO_ASSERT((new_count != 0), "dirty page count overflow for generation %u",
+ new_generation);
+ if (result != VDO_SUCCESS) {
+ enter_zone_read_only_mode(zone, result);
+ return;
+ }
+
+ if (decrement_old)
+ release_generation(zone, old_generation);
+}
+
+static void write_page(struct tree_page *tree_page, struct pooled_vio *vio);
+
+/* Implements waiter_callback_fn */
+static void write_page_callback(struct vdo_waiter *waiter, void *context)
+{
+ write_page(container_of(waiter, struct tree_page, waiter), context);
+}
+
+static void acquire_vio(struct vdo_waiter *waiter, struct block_map_zone *zone)
+{
+ waiter->callback = write_page_callback;
+ acquire_vio_from_pool(zone->vio_pool, waiter);
+}
+
+/* Return: true if all possible generations were not already active */
+static bool attempt_increment(struct block_map_zone *zone)
+{
+ u8 generation = zone->generation + 1;
+
+ if (zone->oldest_generation == generation)
+ return false;
+
+ zone->generation = generation;
+ return true;
+}
+
+/* Launches a flush if one is not already in progress. */
+static void enqueue_page(struct tree_page *page, struct block_map_zone *zone)
+{
+ if ((zone->flusher == NULL) && attempt_increment(zone)) {
+ zone->flusher = page;
+ acquire_vio(&page->waiter, zone);
+ return;
+ }
+
+ vdo_waitq_enqueue_waiter(&zone->flush_waiters, &page->waiter);
+}
+
+static void write_page_if_not_dirtied(struct vdo_waiter *waiter, void *context)
+{
+ struct tree_page *page = container_of(waiter, struct tree_page, waiter);
+ struct write_if_not_dirtied_context *write_context = context;
+
+ if (page->generation == write_context->generation) {
+ acquire_vio(waiter, write_context->zone);
+ return;
+ }
+
+ enqueue_page(page, write_context->zone);
+}
+
+static void return_to_pool(struct block_map_zone *zone, struct pooled_vio *vio)
+{
+ return_vio_to_pool(zone->vio_pool, vio);
+ check_for_drain_complete(zone);
+}
+
+/* This callback is registered in write_initialized_page(). */
+static void finish_page_write(struct vdo_completion *completion)
+{
+ bool dirty;
+ struct vio *vio = as_vio(completion);
+ struct pooled_vio *pooled = container_of(vio, struct pooled_vio, vio);
+ struct tree_page *page = completion->parent;
+ struct block_map_zone *zone = pooled->context;
+
+ vdo_release_recovery_journal_block_reference(zone->block_map->journal,
+ page->writing_recovery_lock,
+ VDO_ZONE_TYPE_LOGICAL,
+ zone->zone_number);
+
+ dirty = (page->writing_generation != page->generation);
+ release_generation(zone, page->writing_generation);
+ page->writing = false;
+
+ if (zone->flusher == page) {
+ struct write_if_not_dirtied_context context = {
+ .zone = zone,
+ .generation = page->writing_generation,
+ };
+
+ vdo_waitq_notify_all_waiters(&zone->flush_waiters,
+ write_page_if_not_dirtied, &context);
+ if (dirty && attempt_increment(zone)) {
+ write_page(page, pooled);
+ return;
+ }
+
+ zone->flusher = NULL;
+ }
+
+ if (dirty) {
+ enqueue_page(page, zone);
+ } else if ((zone->flusher == NULL) && vdo_waitq_has_waiters(&zone->flush_waiters) &&
+ attempt_increment(zone)) {
+ zone->flusher = container_of(vdo_waitq_dequeue_waiter(&zone->flush_waiters),
+ struct tree_page, waiter);
+ write_page(zone->flusher, pooled);
+ return;
+ }
+
+ return_to_pool(zone, pooled);
+}
+
+static void handle_write_error(struct vdo_completion *completion)
+{
+ int result = completion->result;
+ struct vio *vio = as_vio(completion);
+ struct pooled_vio *pooled = container_of(vio, struct pooled_vio, vio);
+ struct block_map_zone *zone = pooled->context;
+
+ vio_record_metadata_io_error(vio);
+ enter_zone_read_only_mode(zone, result);
+ return_to_pool(zone, pooled);
+}
+
+static void write_page_endio(struct bio *bio);
+
+static void write_initialized_page(struct vdo_completion *completion)
+{
+ struct vio *vio = as_vio(completion);
+ struct pooled_vio *pooled = container_of(vio, struct pooled_vio, vio);
+ struct block_map_zone *zone = pooled->context;
+ struct tree_page *tree_page = completion->parent;
+ struct block_map_page *page = (struct block_map_page *) vio->data;
+ blk_opf_t operation = REQ_OP_WRITE | REQ_PRIO;
+
+ /*
+ * Now that we know the page has been written at least once, mark the copy we are writing
+ * as initialized.
+ */
+ page->header.initialized = true;
+
+ if (zone->flusher == tree_page)
+ operation |= REQ_PREFLUSH;
+
+ vdo_submit_metadata_vio(vio, vdo_get_block_map_page_pbn(page),
+ write_page_endio, handle_write_error,
+ operation);
+}
+
+static void write_page_endio(struct bio *bio)
+{
+ struct pooled_vio *vio = bio->bi_private;
+ struct block_map_zone *zone = vio->context;
+ struct block_map_page *page = (struct block_map_page *) vio->vio.data;
+
+ continue_vio_after_io(&vio->vio,
+ (page->header.initialized ?
+ finish_page_write : write_initialized_page),
+ zone->thread_id);
+}
+
+static void write_page(struct tree_page *tree_page, struct pooled_vio *vio)
+{
+ struct vdo_completion *completion = &vio->vio.completion;
+ struct block_map_zone *zone = vio->context;
+ struct block_map_page *page = vdo_as_block_map_page(tree_page);
+
+ if ((zone->flusher != tree_page) &&
+ is_not_older(zone, tree_page->generation, zone->generation)) {
+ /*
+ * This page was re-dirtied after the last flush was issued, hence we need to do
+ * another flush.
+ */
+ enqueue_page(tree_page, zone);
+ return_to_pool(zone, vio);
+ return;
+ }
+
+ completion->parent = tree_page;
+ memcpy(vio->vio.data, tree_page->page_buffer, VDO_BLOCK_SIZE);
+ completion->callback_thread_id = zone->thread_id;
+
+ tree_page->writing = true;
+ tree_page->writing_generation = tree_page->generation;
+ tree_page->writing_recovery_lock = tree_page->recovery_lock;
+
+ /* Clear this now so that we know this page is not on any dirty list. */
+ tree_page->recovery_lock = 0;
+
+ /*
+ * We've already copied the page into the vio which will write it, so if it was not yet
+ * initialized, the first write will indicate that (for torn write protection). It is now
+ * safe to mark it as initialized in memory since if the write fails, the in memory state
+ * will become irrelevant.
+ */
+ if (page->header.initialized) {
+ write_initialized_page(completion);
+ return;
+ }
+
+ page->header.initialized = true;
+ vdo_submit_metadata_vio(&vio->vio, vdo_get_block_map_page_pbn(page),
+ write_page_endio, handle_write_error,
+ REQ_OP_WRITE | REQ_PRIO);
+}
+
+/* Release a lock on a page which was being loaded or allocated. */
+static void release_page_lock(struct data_vio *data_vio, char *what)
+{
+ struct block_map_zone *zone;
+ struct tree_lock *lock_holder;
+ struct tree_lock *lock = &data_vio->tree_lock;
+
+ VDO_ASSERT_LOG_ONLY(lock->locked,
+ "release of unlocked block map page %s for key %llu in tree %u",
+ what, (unsigned long long) lock->key, lock->root_index);
+
+ zone = data_vio->logical.zone->block_map_zone;
+ lock_holder = vdo_int_map_remove(zone->loading_pages, lock->key);
+ VDO_ASSERT_LOG_ONLY((lock_holder == lock),
+ "block map page %s mismatch for key %llu in tree %u",
+ what, (unsigned long long) lock->key, lock->root_index);
+ lock->locked = false;
+}
+
+static void finish_lookup(struct data_vio *data_vio, int result)
+{
+ data_vio->tree_lock.height = 0;
+
+ --data_vio->logical.zone->block_map_zone->active_lookups;
+
+ set_data_vio_logical_callback(data_vio, continue_data_vio_with_block_map_slot);
+ data_vio->vio.completion.error_handler = handle_data_vio_error;
+ continue_data_vio_with_error(data_vio, result);
+}
+
+static void abort_lookup_for_waiter(struct vdo_waiter *waiter, void *context)
+{
+ struct data_vio *data_vio = vdo_waiter_as_data_vio(waiter);
+ int result = *((int *) context);
+
+ if (!data_vio->write) {
+ if (result == VDO_NO_SPACE)
+ result = VDO_SUCCESS;
+ } else if (result != VDO_NO_SPACE) {
+ result = VDO_READ_ONLY;
+ }
+
+ finish_lookup(data_vio, result);
+}
+
+static void abort_lookup(struct data_vio *data_vio, int result, char *what)
+{
+ if (result != VDO_NO_SPACE)
+ enter_zone_read_only_mode(data_vio->logical.zone->block_map_zone, result);
+
+ if (data_vio->tree_lock.locked) {
+ release_page_lock(data_vio, what);
+ vdo_waitq_notify_all_waiters(&data_vio->tree_lock.waiters,
+ abort_lookup_for_waiter,
+ &result);
+ }
+
+ finish_lookup(data_vio, result);
+}
+
+static void abort_load(struct data_vio *data_vio, int result)
+{
+ abort_lookup(data_vio, result, "load");
+}
+
+static bool __must_check is_invalid_tree_entry(const struct vdo *vdo,
+ const struct data_location *mapping,
+ height_t height)
+{
+ if (!vdo_is_valid_location(mapping) ||
+ vdo_is_state_compressed(mapping->state) ||
+ (vdo_is_mapped_location(mapping) && (mapping->pbn == VDO_ZERO_BLOCK)))
+ return true;
+
+ /* Roots aren't physical data blocks, so we can't check their PBNs. */
+ if (height == VDO_BLOCK_MAP_TREE_HEIGHT)
+ return false;
+
+ return !vdo_is_physical_data_block(vdo->depot, mapping->pbn);
+}
+
+static void load_block_map_page(struct block_map_zone *zone, struct data_vio *data_vio);
+static void allocate_block_map_page(struct block_map_zone *zone,
+ struct data_vio *data_vio);
+
+static void continue_with_loaded_page(struct data_vio *data_vio,
+ struct block_map_page *page)
+{
+ struct tree_lock *lock = &data_vio->tree_lock;
+ struct block_map_tree_slot slot = lock->tree_slots[lock->height];
+ struct data_location mapping =
+ vdo_unpack_block_map_entry(&page->entries[slot.block_map_slot.slot]);
+
+ if (is_invalid_tree_entry(vdo_from_data_vio(data_vio), &mapping, lock->height)) {
+ vdo_log_error_strerror(VDO_BAD_MAPPING,
+ "Invalid block map tree PBN: %llu with state %u for page index %u at height %u",
+ (unsigned long long) mapping.pbn, mapping.state,
+ lock->tree_slots[lock->height - 1].page_index,
+ lock->height - 1);
+ abort_load(data_vio, VDO_BAD_MAPPING);
+ return;
+ }
+
+ if (!vdo_is_mapped_location(&mapping)) {
+ /* The page we need is unallocated */
+ allocate_block_map_page(data_vio->logical.zone->block_map_zone,
+ data_vio);
+ return;
+ }
+
+ lock->tree_slots[lock->height - 1].block_map_slot.pbn = mapping.pbn;
+ if (lock->height == 1) {
+ finish_lookup(data_vio, VDO_SUCCESS);
+ return;
+ }
+
+ /* We know what page we need to load next */
+ load_block_map_page(data_vio->logical.zone->block_map_zone, data_vio);
+}
+
+static void continue_load_for_waiter(struct vdo_waiter *waiter, void *context)
+{
+ struct data_vio *data_vio = vdo_waiter_as_data_vio(waiter);
+
+ data_vio->tree_lock.height--;
+ continue_with_loaded_page(data_vio, context);
+}
+
+static void finish_block_map_page_load(struct vdo_completion *completion)
+{
+ physical_block_number_t pbn;
+ struct tree_page *tree_page;
+ struct block_map_page *page;
+ nonce_t nonce;
+ struct vio *vio = as_vio(completion);
+ struct pooled_vio *pooled = vio_as_pooled_vio(vio);
+ struct data_vio *data_vio = completion->parent;
+ struct block_map_zone *zone = pooled->context;
+ struct tree_lock *tree_lock = &data_vio->tree_lock;
+
+ tree_lock->height--;
+ pbn = tree_lock->tree_slots[tree_lock->height].block_map_slot.pbn;
+ tree_page = get_tree_page(zone, tree_lock);
+ page = (struct block_map_page *) tree_page->page_buffer;
+ nonce = zone->block_map->nonce;
+
+ if (!vdo_copy_valid_page(vio->data, nonce, pbn, page))
+ vdo_format_block_map_page(page, nonce, pbn, false);
+ return_vio_to_pool(zone->vio_pool, pooled);
+
+ /* Release our claim to the load and wake any waiters */
+ release_page_lock(data_vio, "load");
+ vdo_waitq_notify_all_waiters(&tree_lock->waiters, continue_load_for_waiter, page);
+ continue_with_loaded_page(data_vio, page);
+}
+
+static void handle_io_error(struct vdo_completion *completion)
+{
+ int result = completion->result;
+ struct vio *vio = as_vio(completion);
+ struct pooled_vio *pooled = container_of(vio, struct pooled_vio, vio);
+ struct data_vio *data_vio = completion->parent;
+ struct block_map_zone *zone = pooled->context;
+
+ vio_record_metadata_io_error(vio);
+ return_vio_to_pool(zone->vio_pool, pooled);
+ abort_load(data_vio, result);
+}
+
+static void load_page_endio(struct bio *bio)
+{
+ struct vio *vio = bio->bi_private;
+ struct data_vio *data_vio = vio->completion.parent;
+
+ continue_vio_after_io(vio, finish_block_map_page_load,
+ data_vio->logical.zone->thread_id);
+}
+
+static void load_page(struct vdo_waiter *waiter, void *context)
+{
+ struct pooled_vio *pooled = context;
+ struct data_vio *data_vio = vdo_waiter_as_data_vio(waiter);
+ struct tree_lock *lock = &data_vio->tree_lock;
+ physical_block_number_t pbn = lock->tree_slots[lock->height - 1].block_map_slot.pbn;
+
+ pooled->vio.completion.parent = data_vio;
+ vdo_submit_metadata_vio(&pooled->vio, pbn, load_page_endio,
+ handle_io_error, REQ_OP_READ | REQ_PRIO);
+}
+
+/*
+ * If the page is already locked, queue up to wait for the lock to be released. If the lock is
+ * acquired, @data_vio->tree_lock.locked will be true.
+ */
+static int attempt_page_lock(struct block_map_zone *zone, struct data_vio *data_vio)
+{
+ int result;
+ struct tree_lock *lock_holder;
+ struct tree_lock *lock = &data_vio->tree_lock;
+ height_t height = lock->height;
+ struct block_map_tree_slot tree_slot = lock->tree_slots[height];
+ union page_key key;
+
+ key.descriptor = (struct page_descriptor) {
+ .root_index = lock->root_index,
+ .height = height,
+ .page_index = tree_slot.page_index,
+ .slot = tree_slot.block_map_slot.slot,
+ };
+ lock->key = key.key;
+
+ result = vdo_int_map_put(zone->loading_pages, lock->key,
+ lock, false, (void **) &lock_holder);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ if (lock_holder == NULL) {
+ /* We got the lock */
+ data_vio->tree_lock.locked = true;
+ return VDO_SUCCESS;
+ }
+
+ /* Someone else is loading or allocating the page we need */
+ vdo_waitq_enqueue_waiter(&lock_holder->waiters, &data_vio->waiter);
+ return VDO_SUCCESS;
+}
+
+/* Load a block map tree page from disk, for the next level in the data vio tree lock. */
+static void load_block_map_page(struct block_map_zone *zone, struct data_vio *data_vio)
+{
+ int result;
+
+ result = attempt_page_lock(zone, data_vio);
+ if (result != VDO_SUCCESS) {
+ abort_load(data_vio, result);
+ return;
+ }
+
+ if (data_vio->tree_lock.locked) {
+ data_vio->waiter.callback = load_page;
+ acquire_vio_from_pool(zone->vio_pool, &data_vio->waiter);
+ }
+}
+
+static void allocation_failure(struct vdo_completion *completion)
+{
+ struct data_vio *data_vio = as_data_vio(completion);
+
+ if (vdo_requeue_completion_if_needed(completion,
+ data_vio->logical.zone->thread_id))
+ return;
+
+ abort_lookup(data_vio, completion->result, "allocation");
+}
+
+static void continue_allocation_for_waiter(struct vdo_waiter *waiter, void *context)
+{
+ struct data_vio *data_vio = vdo_waiter_as_data_vio(waiter);
+ struct tree_lock *tree_lock = &data_vio->tree_lock;
+ physical_block_number_t pbn = *((physical_block_number_t *) context);
+
+ tree_lock->height--;
+ data_vio->tree_lock.tree_slots[tree_lock->height].block_map_slot.pbn = pbn;
+
+ if (tree_lock->height == 0) {
+ finish_lookup(data_vio, VDO_SUCCESS);
+ return;
+ }
+
+ allocate_block_map_page(data_vio->logical.zone->block_map_zone, data_vio);
+}
+
+/** expire_oldest_list() - Expire the oldest list. */
+static void expire_oldest_list(struct dirty_lists *dirty_lists)
+{
+ block_count_t i = dirty_lists->offset++;
+
+ dirty_lists->oldest_period++;
+ if (!list_empty(&dirty_lists->eras[i][VDO_TREE_PAGE])) {
+ list_splice_tail_init(&dirty_lists->eras[i][VDO_TREE_PAGE],
+ &dirty_lists->expired[VDO_TREE_PAGE]);
+ }
+
+ if (!list_empty(&dirty_lists->eras[i][VDO_CACHE_PAGE])) {
+ list_splice_tail_init(&dirty_lists->eras[i][VDO_CACHE_PAGE],
+ &dirty_lists->expired[VDO_CACHE_PAGE]);
+ }
+
+ if (dirty_lists->offset == dirty_lists->maximum_age)
+ dirty_lists->offset = 0;
+}
+
+
+/** update_period() - Update the dirty_lists period if necessary. */
+static void update_period(struct dirty_lists *dirty, sequence_number_t period)
+{
+ while (dirty->next_period <= period) {
+ if ((dirty->next_period - dirty->oldest_period) == dirty->maximum_age)
+ expire_oldest_list(dirty);
+ dirty->next_period++;
+ }
+}
+
+/** write_expired_elements() - Write out the expired list. */
+static void write_expired_elements(struct block_map_zone *zone)
+{
+ struct tree_page *page, *ttmp;
+ struct page_info *info, *ptmp;
+ struct list_head *expired;
+ u8 generation = zone->generation;
+
+ expired = &zone->dirty_lists->expired[VDO_TREE_PAGE];
+ list_for_each_entry_safe(page, ttmp, expired, entry) {
+ int result;
+
+ list_del_init(&page->entry);
+
+ result = VDO_ASSERT(!vdo_waiter_is_waiting(&page->waiter),
+ "Newly expired page not already waiting to write");
+ if (result != VDO_SUCCESS) {
+ enter_zone_read_only_mode(zone, result);
+ continue;
+ }
+
+ set_generation(zone, page, generation);
+ if (!page->writing)
+ enqueue_page(page, zone);
+ }
+
+ expired = &zone->dirty_lists->expired[VDO_CACHE_PAGE];
+ list_for_each_entry_safe(info, ptmp, expired, state_entry) {
+ list_del_init(&info->state_entry);
+ schedule_page_save(info);
+ }
+
+ save_pages(&zone->page_cache);
+}
+
+/**
+ * add_to_dirty_lists() - Add an element to the dirty lists.
+ * @zone: The zone in which we are operating.
+ * @entry: The list entry of the element to add.
+ * @type: The type of page.
+ * @old_period: The period in which the element was previously dirtied, or 0 if it was not dirty.
+ * @new_period: The period in which the element has now been dirtied, or 0 if it does not hold a
+ * lock.
+ */
+static void add_to_dirty_lists(struct block_map_zone *zone,
+ struct list_head *entry,
+ enum block_map_page_type type,
+ sequence_number_t old_period,
+ sequence_number_t new_period)
+{
+ struct dirty_lists *dirty_lists = zone->dirty_lists;
+
+ if ((old_period == new_period) || ((old_period != 0) && (old_period < new_period)))
+ return;
+
+ if (new_period < dirty_lists->oldest_period) {
+ list_move_tail(entry, &dirty_lists->expired[type]);
+ } else {
+ update_period(dirty_lists, new_period);
+ list_move_tail(entry,
+ &dirty_lists->eras[new_period % dirty_lists->maximum_age][type]);
+ }
+
+ write_expired_elements(zone);
+}
+
+/*
+ * Record the allocation in the tree and wake any waiters now that the write lock has been
+ * released.
+ */
+static void finish_block_map_allocation(struct vdo_completion *completion)
+{
+ physical_block_number_t pbn;
+ struct tree_page *tree_page;
+ struct block_map_page *page;
+ sequence_number_t old_lock;
+ struct data_vio *data_vio = as_data_vio(completion);
+ struct block_map_zone *zone = data_vio->logical.zone->block_map_zone;
+ struct tree_lock *tree_lock = &data_vio->tree_lock;
+ height_t height = tree_lock->height;
+
+ assert_data_vio_in_logical_zone(data_vio);
+
+ tree_page = get_tree_page(zone, tree_lock);
+ pbn = tree_lock->tree_slots[height - 1].block_map_slot.pbn;
+
+ /* Record the allocation. */
+ page = (struct block_map_page *) tree_page->page_buffer;
+ old_lock = tree_page->recovery_lock;
+ vdo_update_block_map_page(page, data_vio, pbn,
+ VDO_MAPPING_STATE_UNCOMPRESSED,
+ &tree_page->recovery_lock);
+
+ if (vdo_waiter_is_waiting(&tree_page->waiter)) {
+ /* This page is waiting to be written out. */
+ if (zone->flusher != tree_page) {
+ /*
+ * The outstanding flush won't cover the update we just made,
+ * so mark the page as needing another flush.
+ */
+ set_generation(zone, tree_page, zone->generation);
+ }
+ } else {
+ /* Put the page on a dirty list */
+ if (old_lock == 0)
+ INIT_LIST_HEAD(&tree_page->entry);
+ add_to_dirty_lists(zone, &tree_page->entry, VDO_TREE_PAGE,
+ old_lock, tree_page->recovery_lock);
+ }
+
+ tree_lock->height--;
+ if (height > 1) {
+ /* Format the interior node we just allocated (in memory). */
+ tree_page = get_tree_page(zone, tree_lock);
+ vdo_format_block_map_page(tree_page->page_buffer,
+ zone->block_map->nonce,
+ pbn, false);
+ }
+
+ /* Release our claim to the allocation and wake any waiters */
+ release_page_lock(data_vio, "allocation");
+ vdo_waitq_notify_all_waiters(&tree_lock->waiters,
+ continue_allocation_for_waiter, &pbn);
+ if (tree_lock->height == 0) {
+ finish_lookup(data_vio, VDO_SUCCESS);
+ return;
+ }
+
+ allocate_block_map_page(zone, data_vio);
+}
+
+static void release_block_map_write_lock(struct vdo_completion *completion)
+{
+ struct data_vio *data_vio = as_data_vio(completion);
+
+ assert_data_vio_in_allocated_zone(data_vio);
+
+ release_data_vio_allocation_lock(data_vio, true);
+ launch_data_vio_logical_callback(data_vio, finish_block_map_allocation);
+}
+
+/*
+ * Newly allocated block map pages are set to have to MAXIMUM_REFERENCES after they are journaled,
+ * to prevent deduplication against the block after we release the write lock on it, but before we
+ * write out the page.
+ */
+static void set_block_map_page_reference_count(struct vdo_completion *completion)
+{
+ struct data_vio *data_vio = as_data_vio(completion);
+
+ assert_data_vio_in_allocated_zone(data_vio);
+
+ completion->callback = release_block_map_write_lock;
+ vdo_modify_reference_count(completion, &data_vio->increment_updater);
+}
+
+static void journal_block_map_allocation(struct vdo_completion *completion)
+{
+ struct data_vio *data_vio = as_data_vio(completion);
+
+ assert_data_vio_in_journal_zone(data_vio);
+
+ set_data_vio_allocated_zone_callback(data_vio,
+ set_block_map_page_reference_count);
+ vdo_add_recovery_journal_entry(completion->vdo->recovery_journal, data_vio);
+}
+
+static void allocate_block(struct vdo_completion *completion)
+{
+ struct data_vio *data_vio = as_data_vio(completion);
+ struct tree_lock *lock = &data_vio->tree_lock;
+ physical_block_number_t pbn;
+
+ assert_data_vio_in_allocated_zone(data_vio);
+
+ if (!vdo_allocate_block_in_zone(data_vio))
+ return;
+
+ pbn = data_vio->allocation.pbn;
+ lock->tree_slots[lock->height - 1].block_map_slot.pbn = pbn;
+ data_vio->increment_updater = (struct reference_updater) {
+ .operation = VDO_JOURNAL_BLOCK_MAP_REMAPPING,
+ .increment = true,
+ .zpbn = {
+ .pbn = pbn,
+ .state = VDO_MAPPING_STATE_UNCOMPRESSED,
+ },
+ .lock = data_vio->allocation.lock,
+ };
+
+ launch_data_vio_journal_callback(data_vio, journal_block_map_allocation);
+}
+
+static void allocate_block_map_page(struct block_map_zone *zone,
+ struct data_vio *data_vio)
+{
+ int result;
+
+ if (!data_vio->write || data_vio->is_discard) {
+ /* This is a pure read or a discard, so there's nothing left to do here. */
+ finish_lookup(data_vio, VDO_SUCCESS);
+ return;
+ }
+
+ result = attempt_page_lock(zone, data_vio);
+ if (result != VDO_SUCCESS) {
+ abort_lookup(data_vio, result, "allocation");
+ return;
+ }
+
+ if (!data_vio->tree_lock.locked)
+ return;
+
+ data_vio_allocate_data_block(data_vio, VIO_BLOCK_MAP_WRITE_LOCK,
+ allocate_block, allocation_failure);
+}
+
+/**
+ * vdo_find_block_map_slot() - Find the block map slot in which the block map entry for a data_vio
+ * resides and cache that result in the data_vio.
+ *
+ * All ancestors in the tree will be allocated or loaded, as needed.
+ */
+void vdo_find_block_map_slot(struct data_vio *data_vio)
+{
+ page_number_t page_index;
+ struct block_map_tree_slot tree_slot;
+ struct data_location mapping;
+ struct block_map_page *page = NULL;
+ struct tree_lock *lock = &data_vio->tree_lock;
+ struct block_map_zone *zone = data_vio->logical.zone->block_map_zone;
+
+ zone->active_lookups++;
+ if (vdo_is_state_draining(&zone->state)) {
+ finish_lookup(data_vio, VDO_SHUTTING_DOWN);
+ return;
+ }
+
+ lock->tree_slots[0].block_map_slot.slot =
+ data_vio->logical.lbn % VDO_BLOCK_MAP_ENTRIES_PER_PAGE;
+ page_index = (lock->tree_slots[0].page_index / zone->block_map->root_count);
+ tree_slot = (struct block_map_tree_slot) {
+ .page_index = page_index / VDO_BLOCK_MAP_ENTRIES_PER_PAGE,
+ .block_map_slot = {
+ .pbn = 0,
+ .slot = page_index % VDO_BLOCK_MAP_ENTRIES_PER_PAGE,
+ },
+ };
+
+ for (lock->height = 1; lock->height <= VDO_BLOCK_MAP_TREE_HEIGHT; lock->height++) {
+ physical_block_number_t pbn;
+
+ lock->tree_slots[lock->height] = tree_slot;
+ page = (struct block_map_page *) (get_tree_page(zone, lock)->page_buffer);
+ pbn = vdo_get_block_map_page_pbn(page);
+ if (pbn != VDO_ZERO_BLOCK) {
+ lock->tree_slots[lock->height].block_map_slot.pbn = pbn;
+ break;
+ }
+
+ /* Calculate the index and slot for the next level. */
+ tree_slot.block_map_slot.slot =
+ tree_slot.page_index % VDO_BLOCK_MAP_ENTRIES_PER_PAGE;
+ tree_slot.page_index = tree_slot.page_index / VDO_BLOCK_MAP_ENTRIES_PER_PAGE;
+ }
+
+ /* The page at this height has been allocated and loaded. */
+ mapping = vdo_unpack_block_map_entry(&page->entries[tree_slot.block_map_slot.slot]);
+ if (is_invalid_tree_entry(vdo_from_data_vio(data_vio), &mapping, lock->height)) {
+ vdo_log_error_strerror(VDO_BAD_MAPPING,
+ "Invalid block map tree PBN: %llu with state %u for page index %u at height %u",
+ (unsigned long long) mapping.pbn, mapping.state,
+ lock->tree_slots[lock->height - 1].page_index,
+ lock->height - 1);
+ abort_load(data_vio, VDO_BAD_MAPPING);
+ return;
+ }
+
+ if (!vdo_is_mapped_location(&mapping)) {
+ /* The page we want one level down has not been allocated, so allocate it. */
+ allocate_block_map_page(zone, data_vio);
+ return;
+ }
+
+ lock->tree_slots[lock->height - 1].block_map_slot.pbn = mapping.pbn;
+ if (lock->height == 1) {
+ /* This is the ultimate block map page, so we're done */
+ finish_lookup(data_vio, VDO_SUCCESS);
+ return;
+ }
+
+ /* We know what page we need to load. */
+ load_block_map_page(zone, data_vio);
+}
+
+/*
+ * Find the PBN of a leaf block map page. This method may only be used after all allocated tree
+ * pages have been loaded, otherwise, it may give the wrong answer (0).
+ */
+physical_block_number_t vdo_find_block_map_page_pbn(struct block_map *map,
+ page_number_t page_number)
+{
+ struct data_location mapping;
+ struct tree_page *tree_page;
+ struct block_map_page *page;
+ root_count_t root_index = page_number % map->root_count;
+ page_number_t page_index = page_number / map->root_count;
+ slot_number_t slot = page_index % VDO_BLOCK_MAP_ENTRIES_PER_PAGE;
+
+ page_index /= VDO_BLOCK_MAP_ENTRIES_PER_PAGE;
+
+ tree_page = get_tree_page_by_index(map->forest, root_index, 1, page_index);
+ page = (struct block_map_page *) tree_page->page_buffer;
+ if (!page->header.initialized)
+ return VDO_ZERO_BLOCK;
+
+ mapping = vdo_unpack_block_map_entry(&page->entries[slot]);
+ if (!vdo_is_valid_location(&mapping) || vdo_is_state_compressed(mapping.state))
+ return VDO_ZERO_BLOCK;
+ return mapping.pbn;
+}
+
+/*
+ * Write a tree page or indicate that it has been re-dirtied if it is already being written. This
+ * method is used when correcting errors in the tree during read-only rebuild.
+ */
+void vdo_write_tree_page(struct tree_page *page, struct block_map_zone *zone)
+{
+ bool waiting = vdo_waiter_is_waiting(&page->waiter);
+
+ if (waiting && (zone->flusher == page))
+ return;
+
+ set_generation(zone, page, zone->generation);
+ if (waiting || page->writing)
+ return;
+
+ enqueue_page(page, zone);
+}
+
+static int make_segment(struct forest *old_forest, block_count_t new_pages,
+ struct boundary *new_boundary, struct forest *forest)
+{
+ size_t index = (old_forest == NULL) ? 0 : old_forest->segments;
+ struct tree_page *page_ptr;
+ page_count_t segment_sizes[VDO_BLOCK_MAP_TREE_HEIGHT];
+ height_t height;
+ root_count_t root;
+ int result;
+
+ forest->segments = index + 1;
+
+ result = vdo_allocate(forest->segments, struct boundary,
+ "forest boundary array", &forest->boundaries);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = vdo_allocate(forest->segments, struct tree_page *,
+ "forest page pointers", &forest->pages);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = vdo_allocate(new_pages, struct tree_page,
+ "new forest pages", &forest->pages[index]);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ if (index > 0) {
+ memcpy(forest->boundaries, old_forest->boundaries,
+ index * sizeof(struct boundary));
+ memcpy(forest->pages, old_forest->pages,
+ index * sizeof(struct tree_page *));
+ }
+
+ memcpy(&(forest->boundaries[index]), new_boundary, sizeof(struct boundary));
+
+ for (height = 0; height < VDO_BLOCK_MAP_TREE_HEIGHT; height++) {
+ segment_sizes[height] = new_boundary->levels[height];
+ if (index > 0)
+ segment_sizes[height] -= old_forest->boundaries[index - 1].levels[height];
+ }
+
+ page_ptr = forest->pages[index];
+ for (root = 0; root < forest->map->root_count; root++) {
+ struct block_map_tree_segment *segment;
+ struct block_map_tree *tree = &(forest->trees[root]);
+ height_t height;
+
+ int result = vdo_allocate(forest->segments,
+ struct block_map_tree_segment,
+ "tree root segments", &tree->segments);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ if (index > 0) {
+ memcpy(tree->segments, old_forest->trees[root].segments,
+ index * sizeof(struct block_map_tree_segment));
+ }
+
+ segment = &(tree->segments[index]);
+ for (height = 0; height < VDO_BLOCK_MAP_TREE_HEIGHT; height++) {
+ if (segment_sizes[height] == 0)
+ continue;
+
+ segment->levels[height] = page_ptr;
+ if (height == (VDO_BLOCK_MAP_TREE_HEIGHT - 1)) {
+ /* Record the root. */
+ struct block_map_page *page =
+ vdo_format_block_map_page(page_ptr->page_buffer,
+ forest->map->nonce,
+ VDO_INVALID_PBN, true);
+ page->entries[0] =
+ vdo_pack_block_map_entry(forest->map->root_origin + root,
+ VDO_MAPPING_STATE_UNCOMPRESSED);
+ }
+ page_ptr += segment_sizes[height];
+ }
+ }
+
+ return VDO_SUCCESS;
+}
+
+static void deforest(struct forest *forest, size_t first_page_segment)
+{
+ root_count_t root;
+
+ if (forest->pages != NULL) {
+ size_t segment;
+
+ for (segment = first_page_segment; segment < forest->segments; segment++)
+ vdo_free(forest->pages[segment]);
+ vdo_free(forest->pages);
+ }
+
+ for (root = 0; root < forest->map->root_count; root++)
+ vdo_free(forest->trees[root].segments);
+
+ vdo_free(forest->boundaries);
+ vdo_free(forest);
+}
+
+/**
+ * make_forest() - Make a collection of trees for a block_map, expanding the existing forest if
+ * there is one.
+ * @entries: The number of entries the block map will hold.
+ *
+ * Return: VDO_SUCCESS or an error.
+ */
+static int make_forest(struct block_map *map, block_count_t entries)
+{
+ struct forest *forest, *old_forest = map->forest;
+ struct boundary new_boundary, *old_boundary = NULL;
+ block_count_t new_pages;
+ int result;
+
+ if (old_forest != NULL)
+ old_boundary = &(old_forest->boundaries[old_forest->segments - 1]);
+
+ new_pages = vdo_compute_new_forest_pages(map->root_count, old_boundary,
+ entries, &new_boundary);
+ if (new_pages == 0) {
+ map->next_entry_count = entries;
+ return VDO_SUCCESS;
+ }
+
+ result = vdo_allocate_extended(struct forest, map->root_count,
+ struct block_map_tree, __func__,
+ &forest);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ forest->map = map;
+ result = make_segment(old_forest, new_pages, &new_boundary, forest);
+ if (result != VDO_SUCCESS) {
+ deforest(forest, forest->segments - 1);
+ return result;
+ }
+
+ map->next_forest = forest;
+ map->next_entry_count = entries;
+ return VDO_SUCCESS;
+}
+
+/**
+ * replace_forest() - Replace a block_map's forest with the already-prepared larger forest.
+ */
+static void replace_forest(struct block_map *map)
+{
+ if (map->next_forest != NULL) {
+ if (map->forest != NULL)
+ deforest(map->forest, map->forest->segments);
+ map->forest = vdo_forget(map->next_forest);
+ }
+
+ map->entry_count = map->next_entry_count;
+ map->next_entry_count = 0;
+}
+
+/**
+ * finish_cursor() - Finish the traversal of a single tree. If it was the last cursor, finish the
+ * traversal.
+ */
+static void finish_cursor(struct cursor *cursor)
+{
+ struct cursors *cursors = cursor->parent;
+ struct vdo_completion *completion = cursors->completion;
+
+ return_vio_to_pool(cursors->pool, vdo_forget(cursor->vio));
+ if (--cursors->active_roots > 0)
+ return;
+
+ vdo_free(cursors);
+
+ vdo_finish_completion(completion);
+}
+
+static void traverse(struct cursor *cursor);
+
+/**
+ * continue_traversal() - Continue traversing a block map tree.
+ * @completion: The VIO doing a read or write.
+ */
+static void continue_traversal(struct vdo_completion *completion)
+{
+ vio_record_metadata_io_error(as_vio(completion));
+ traverse(completion->parent);
+}
+
+/**
+ * finish_traversal_load() - Continue traversing a block map tree now that a page has been loaded.
+ * @completion: The VIO doing the read.
+ */
+static void finish_traversal_load(struct vdo_completion *completion)
+{
+ struct cursor *cursor = completion->parent;
+ height_t height = cursor->height;
+ struct cursor_level *level = &cursor->levels[height];
+ struct tree_page *tree_page =
+ &(cursor->tree->segments[0].levels[height][level->page_index]);
+ struct block_map_page *page = (struct block_map_page *) tree_page->page_buffer;
+
+ vdo_copy_valid_page(cursor->vio->vio.data,
+ cursor->parent->zone->block_map->nonce,
+ pbn_from_vio_bio(cursor->vio->vio.bio), page);
+ traverse(cursor);
+}
+
+static void traversal_endio(struct bio *bio)
+{
+ struct vio *vio = bio->bi_private;
+ struct cursor *cursor = vio->completion.parent;
+
+ continue_vio_after_io(vio, finish_traversal_load,
+ cursor->parent->zone->thread_id);
+}
+
+/**
+ * traverse() - Traverse a single block map tree.
+ *
+ * This is the recursive heart of the traversal process.
+ */
+static void traverse(struct cursor *cursor)
+{
+ for (; cursor->height < VDO_BLOCK_MAP_TREE_HEIGHT; cursor->height++) {
+ height_t height = cursor->height;
+ struct cursor_level *level = &cursor->levels[height];
+ struct tree_page *tree_page =
+ &(cursor->tree->segments[0].levels[height][level->page_index]);
+ struct block_map_page *page = (struct block_map_page *) tree_page->page_buffer;
+
+ if (!page->header.initialized)
+ continue;
+
+ for (; level->slot < VDO_BLOCK_MAP_ENTRIES_PER_PAGE; level->slot++) {
+ struct cursor_level *next_level;
+ page_number_t entry_index =
+ (VDO_BLOCK_MAP_ENTRIES_PER_PAGE * level->page_index) + level->slot;
+ struct data_location location =
+ vdo_unpack_block_map_entry(&page->entries[level->slot]);
+
+ if (!vdo_is_valid_location(&location)) {
+ /* This entry is invalid, so remove it from the page. */
+ page->entries[level->slot] = UNMAPPED_BLOCK_MAP_ENTRY;
+ vdo_write_tree_page(tree_page, cursor->parent->zone);
+ continue;
+ }
+
+ if (!vdo_is_mapped_location(&location))
+ continue;
+
+ /* Erase mapped entries past the end of the logical space. */
+ if (entry_index >= cursor->boundary.levels[height]) {
+ page->entries[level->slot] = UNMAPPED_BLOCK_MAP_ENTRY;
+ vdo_write_tree_page(tree_page, cursor->parent->zone);
+ continue;
+ }
+
+ if (cursor->height < VDO_BLOCK_MAP_TREE_HEIGHT - 1) {
+ int result = cursor->parent->entry_callback(location.pbn,
+ cursor->parent->completion);
+ if (result != VDO_SUCCESS) {
+ page->entries[level->slot] = UNMAPPED_BLOCK_MAP_ENTRY;
+ vdo_write_tree_page(tree_page, cursor->parent->zone);
+ continue;
+ }
+ }
+
+ if (cursor->height == 0)
+ continue;
+
+ cursor->height--;
+ next_level = &cursor->levels[cursor->height];
+ next_level->page_index = entry_index;
+ next_level->slot = 0;
+ level->slot++;
+ vdo_submit_metadata_vio(&cursor->vio->vio, location.pbn,
+ traversal_endio, continue_traversal,
+ REQ_OP_READ | REQ_PRIO);
+ return;
+ }
+ }
+
+ finish_cursor(cursor);
+}
+
+/**
+ * launch_cursor() - Start traversing a single block map tree now that the cursor has a VIO with
+ * which to load pages.
+ * @context: The pooled_vio just acquired.
+ *
+ * Implements waiter_callback_fn.
+ */
+static void launch_cursor(struct vdo_waiter *waiter, void *context)
+{
+ struct cursor *cursor = container_of(waiter, struct cursor, waiter);
+ struct pooled_vio *pooled = context;
+
+ cursor->vio = pooled;
+ pooled->vio.completion.parent = cursor;
+ pooled->vio.completion.callback_thread_id = cursor->parent->zone->thread_id;
+ traverse(cursor);
+}
+
+/**
+ * compute_boundary() - Compute the number of pages used at each level of the given root's tree.
+ *
+ * Return: The list of page counts as a boundary structure.
+ */
+static struct boundary compute_boundary(struct block_map *map, root_count_t root_index)
+{
+ struct boundary boundary;
+ height_t height;
+ page_count_t leaf_pages = vdo_compute_block_map_page_count(map->entry_count);
+ /*
+ * Compute the leaf pages for this root. If the number of leaf pages does not distribute
+ * evenly, we must determine if this root gets an extra page. Extra pages are assigned to
+ * roots starting from tree 0.
+ */
+ page_count_t last_tree_root = (leaf_pages - 1) % map->root_count;
+ page_count_t level_pages = leaf_pages / map->root_count;
+
+ if (root_index <= last_tree_root)
+ level_pages++;
+
+ for (height = 0; height < VDO_BLOCK_MAP_TREE_HEIGHT - 1; height++) {
+ boundary.levels[height] = level_pages;
+ level_pages = DIV_ROUND_UP(level_pages, VDO_BLOCK_MAP_ENTRIES_PER_PAGE);
+ }
+
+ /* The root node always exists, even if the root is otherwise unused. */
+ boundary.levels[VDO_BLOCK_MAP_TREE_HEIGHT - 1] = 1;
+
+ return boundary;
+}
+
+/**
+ * vdo_traverse_forest() - Walk the entire forest of a block map.
+ * @callback: A function to call with the pbn of each allocated node in the forest.
+ * @completion: The completion to notify on each traversed PBN, and when traversal completes.
+ */
+void vdo_traverse_forest(struct block_map *map, vdo_entry_callback_fn callback,
+ struct vdo_completion *completion)
+{
+ root_count_t root;
+ struct cursors *cursors;
+ int result;
+
+ result = vdo_allocate_extended(struct cursors, map->root_count,
+ struct cursor, __func__, &cursors);
+ if (result != VDO_SUCCESS) {
+ vdo_fail_completion(completion, result);
+ return;
+ }
+
+ cursors->zone = &map->zones[0];
+ cursors->pool = cursors->zone->vio_pool;
+ cursors->entry_callback = callback;
+ cursors->completion = completion;
+ cursors->active_roots = map->root_count;
+ for (root = 0; root < map->root_count; root++) {
+ struct cursor *cursor = &cursors->cursors[root];
+
+ *cursor = (struct cursor) {
+ .tree = &map->forest->trees[root],
+ .height = VDO_BLOCK_MAP_TREE_HEIGHT - 1,
+ .parent = cursors,
+ .boundary = compute_boundary(map, root),
+ };
+
+ cursor->waiter.callback = launch_cursor;
+ acquire_vio_from_pool(cursors->pool, &cursor->waiter);
+ }
+}
+
+/**
+ * initialize_block_map_zone() - Initialize the per-zone portions of the block map.
+ * @maximum_age: The number of journal blocks before a dirtied page is considered old and must be
+ * written out.
+ */
+static int __must_check initialize_block_map_zone(struct block_map *map,
+ zone_count_t zone_number,
+ page_count_t cache_size,
+ block_count_t maximum_age)
+{
+ int result;
+ block_count_t i;
+ struct vdo *vdo = map->vdo;
+ struct block_map_zone *zone = &map->zones[zone_number];
+
+ BUILD_BUG_ON(sizeof(struct page_descriptor) != sizeof(u64));
+
+ zone->zone_number = zone_number;
+ zone->thread_id = vdo->thread_config.logical_threads[zone_number];
+ zone->block_map = map;
+
+ result = vdo_allocate_extended(struct dirty_lists, maximum_age,
+ dirty_era_t, __func__,
+ &zone->dirty_lists);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ zone->dirty_lists->maximum_age = maximum_age;
+ INIT_LIST_HEAD(&zone->dirty_lists->expired[VDO_TREE_PAGE]);
+ INIT_LIST_HEAD(&zone->dirty_lists->expired[VDO_CACHE_PAGE]);
+
+ for (i = 0; i < maximum_age; i++) {
+ INIT_LIST_HEAD(&zone->dirty_lists->eras[i][VDO_TREE_PAGE]);
+ INIT_LIST_HEAD(&zone->dirty_lists->eras[i][VDO_CACHE_PAGE]);
+ }
+
+ result = vdo_int_map_create(VDO_LOCK_MAP_CAPACITY, &zone->loading_pages);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = make_vio_pool(vdo, BLOCK_MAP_VIO_POOL_SIZE,
+ zone->thread_id, VIO_TYPE_BLOCK_MAP_INTERIOR,
+ VIO_PRIORITY_METADATA, zone, &zone->vio_pool);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ vdo_set_admin_state_code(&zone->state, VDO_ADMIN_STATE_NORMAL_OPERATION);
+
+ zone->page_cache.zone = zone;
+ zone->page_cache.vdo = vdo;
+ zone->page_cache.page_count = cache_size / map->zone_count;
+ zone->page_cache.stats.free_pages = zone->page_cache.page_count;
+
+ result = allocate_cache_components(&zone->page_cache);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ /* initialize empty circular queues */
+ INIT_LIST_HEAD(&zone->page_cache.lru_list);
+ INIT_LIST_HEAD(&zone->page_cache.outgoing_list);
+
+ return VDO_SUCCESS;
+}
+
+/* Implements vdo_zone_thread_getter_fn */
+static thread_id_t get_block_map_zone_thread_id(void *context, zone_count_t zone_number)
+{
+ struct block_map *map = context;
+
+ return map->zones[zone_number].thread_id;
+}
+
+/* Implements vdo_action_preamble_fn */
+static void prepare_for_era_advance(void *context, struct vdo_completion *parent)
+{
+ struct block_map *map = context;
+
+ map->current_era_point = map->pending_era_point;
+ vdo_finish_completion(parent);
+}
+
+/* Implements vdo_zone_action_fn */
+static void advance_block_map_zone_era(void *context, zone_count_t zone_number,
+ struct vdo_completion *parent)
+{
+ struct block_map *map = context;
+ struct block_map_zone *zone = &map->zones[zone_number];
+
+ update_period(zone->dirty_lists, map->current_era_point);
+ write_expired_elements(zone);
+ vdo_finish_completion(parent);
+}
+
+/*
+ * Schedule an era advance if necessary. This method should not be called directly. Rather, call
+ * vdo_schedule_default_action() on the block map's action manager.
+ *
+ * Implements vdo_action_scheduler_fn.
+ */
+static bool schedule_era_advance(void *context)
+{
+ struct block_map *map = context;
+
+ if (map->current_era_point == map->pending_era_point)
+ return false;
+
+ return vdo_schedule_action(map->action_manager, prepare_for_era_advance,
+ advance_block_map_zone_era, NULL, NULL);
+}
+
+static void uninitialize_block_map_zone(struct block_map_zone *zone)
+{
+ struct vdo_page_cache *cache = &zone->page_cache;
+
+ vdo_free(vdo_forget(zone->dirty_lists));
+ free_vio_pool(vdo_forget(zone->vio_pool));
+ vdo_int_map_free(vdo_forget(zone->loading_pages));
+ if (cache->infos != NULL) {
+ struct page_info *info;
+
+ for (info = cache->infos; info < cache->infos + cache->page_count; info++)
+ free_vio(vdo_forget(info->vio));
+ }
+
+ vdo_int_map_free(vdo_forget(cache->page_map));
+ vdo_free(vdo_forget(cache->infos));
+ vdo_free(vdo_forget(cache->pages));
+}
+
+void vdo_free_block_map(struct block_map *map)
+{
+ zone_count_t zone;
+
+ if (map == NULL)
+ return;
+
+ for (zone = 0; zone < map->zone_count; zone++)
+ uninitialize_block_map_zone(&map->zones[zone]);
+
+ vdo_abandon_block_map_growth(map);
+ if (map->forest != NULL)
+ deforest(vdo_forget(map->forest), 0);
+ vdo_free(vdo_forget(map->action_manager));
+ vdo_free(map);
+}
+
+/* @journal may be NULL. */
+int vdo_decode_block_map(struct block_map_state_2_0 state, block_count_t logical_blocks,
+ struct vdo *vdo, struct recovery_journal *journal,
+ nonce_t nonce, page_count_t cache_size, block_count_t maximum_age,
+ struct block_map **map_ptr)
+{
+ struct block_map *map;
+ int result;
+ zone_count_t zone = 0;
+
+ BUILD_BUG_ON(VDO_BLOCK_MAP_ENTRIES_PER_PAGE !=
+ ((VDO_BLOCK_SIZE - sizeof(struct block_map_page)) /
+ sizeof(struct block_map_entry)));
+ result = VDO_ASSERT(cache_size > 0, "block map cache size is specified");
+ if (result != VDO_SUCCESS)
+ return result;
+
+ result = vdo_allocate_extended(struct block_map,
+ vdo->thread_config.logical_zone_count,
+ struct block_map_zone, __func__, &map);
+ if (result != VDO_SUCCESS)
+ return result;
+
+ map->vdo = vdo;
+ map->root_origin = state.root_origin;
+ map->root_count = state.root_count;
+ map->entry_count = logical_blocks;
+ map->journal = journal;
+ map->nonce = nonce;
+
+ result = make_forest(map, map->entry_count);
+ if (result != VDO_SUCCESS) {
+ vdo_free_block_map(map);
+ return result;
+ }
+
+ replace_forest(map);
+
+ map->zone_count = vdo->thread_config.logical_zone_count;
+ for (zone = 0; zone < map->zone_count; zone++) {
+ result = initialize_block_map_zone(map, zone, cache_size, maximum_age);
+ if (result != VDO_SUCCESS) {
+ vdo_free_block_map(map);
+ return result;
+ }
+ }
+
+ result = vdo_make_action_manager(map->zone_count, get_block_map_zone_thread_id,
+ vdo_get_recovery_journal_thread_id(journal),
+ map, schedule_era_advance, vdo,
+ &map->action_manager);
+ if (result != VDO_SUCCESS) {
+ vdo_free_block_map(map);
+ return result;
+ }
+
+ *map_ptr = map;
+ return VDO_SUCCESS;
+}
+
+struct block_map_state_2_0 vdo_record_block_map(const struct block_map *map)
+{
+ return (struct block_map_state_2_0) {
+ .flat_page_origin = VDO_BLOCK_MAP_FLAT_PAGE_ORIGIN,
+ /* This is the flat page count, which has turned out to always be 0. */
+ .flat_page_count = 0,
+ .root_origin = map->root_origin,
+ .root_count = map->root_count,
+ };
+}
+
+/* The block map needs to know the journals' sequence number to initialize the eras. */
+void vdo_initialize_block_map_from_journal(struct block_map *map,
+ struct recovery_journal *journal)
+{
+ zone_count_t z = 0;
+
+ map->current_era_point = vdo_get_recovery_journal_current_sequence_number(journal);
+ map->pending_era_point = map->current_era_point;
+
+ for (z = 0; z < map->zone_count; z++) {
+ struct dirty_lists *dirty_lists = map->zones[z].dirty_lists;
+
+ VDO_ASSERT_LOG_ONLY(dirty_lists->next_period == 0, "current period not set");
+ dirty_lists->oldest_period = map->current_era_point;
+ dirty_lists->next_period = map->current_era_point + 1;
+ dirty_lists->offset = map->current_era_point % dirty_lists->maximum_age;
+ }
+}
+
+/* Compute the logical zone for the LBN of a data vio. */
+zone_count_t vdo_compute_logical_zone(struct data_vio *data_vio)
+{
+ struct block_map *map = vdo_from_data_vio(data_vio)->block_map;
+ struct tree_lock *tree_lock = &data_vio->tree_lock;
+ page_number_t page_number = data_vio->logical.lbn / VDO_BLOCK_MAP_ENTRIES_PER_PAGE;
+
+ tree_lock->tree_slots[0].page_index = page_number;
+ tree_lock->root_index = page_number % map->root_count;
+ return (tree_lock->root_index % map->zone_count);
+}
+
+void vdo_advance_block_map_era(struct block_map *map,
+ sequence_number_t recovery_block_number)
+{
+ if (map == NULL)
+ return;
+
+ map->pending_era_point = recovery_block_number;
+ vdo_schedule_default_action(map->action_manager);
+}
+
+/* Implements vdo_admin_initiator_fn */
+static void initiate_drain(struct admin_state *state)
+{
+ struct block_map_zone *zone = container_of(state, struct block_map_zone, state);
+
+ VDO_ASSERT_LOG_ONLY((zone->active_lookups == 0),
+ "%s() called with no active lookups", __func__);
+
+ if (!vdo_is_state_suspending(state)) {
+ while (zone->dirty_lists->oldest_period < zone->dirty_lists->next_period)
+ expire_oldest_list(zone->dirty_lists);
+ write_expired_elements(zone);
+ }
+
+ check_for_drain_complete(zone);
+}
+
+/* Implements vdo_zone_action_fn. */
+static void drain_zone(void *context, zone_count_t zone_number,
+ struct vdo_completion *parent)
+{
+ struct block_map *map = context;
+ struct block_map_zone *zone = &map->zones[zone_number];
+
+ vdo_start_draining(&zone->state,
+ vdo_get_current_manager_operation(map->action_manager),
+ parent, initiate_drain);
+}
+
+void vdo_drain_block_map(struct block_map *map, const struct admin_state_code *operation,
+ struct vdo_completion *parent)
+{
+ vdo_schedule_operation(map->action_manager, operation, NULL, drain_zone, NULL,
+ parent);
+}
+
+/* Implements vdo_zone_action_fn. */
+static void resume_block_map_zone(void *context, zone_count_t zone_number,
+ struct vdo_completion *parent)
+{
+ struct block_map *map = context;
+ struct block_map_zone *zone = &map->zones[zone_number];
+
+ vdo_fail_completion(parent, vdo_resume_if_quiescent(&zone->state));
+}
+
+void vdo_resume_block_map(struct block_map *map, struct vdo_completion *parent)
+{
+ vdo_schedule_operation(map->action_manager, VDO_ADMIN_STATE_RESUMING,
+ NULL, resume_block_map_zone, NULL, parent);
+}
+
+/* Allocate an expanded collection of trees, for a future growth. */
+int vdo_prepare_to_grow_block_map(struct block_map *map,
+ block_count_t new_logical_blocks)
+{
+ if (map->next_entry_count == new_logical_blocks)
+ return VDO_SUCCESS;
+
+ if (map->next_entry_count > 0)
+ vdo_abandon_block_map_growth(map);
+
+ if (new_logical_blocks < map->entry_count) {
+ map->next_entry_count = map->entry_count;
+ return VDO_SUCCESS;
+ }
+
+ return make_forest(map, new_logical_blocks);
+}
+
+/* Implements vdo_action_preamble_fn */
+static void grow_forest(void *context, struct vdo_completion *completion)
+{
+ replace_forest(context);
+ vdo_finish_completion(completion);
+}
+
+/* Requires vdo_prepare_to_grow_block_map() to have been previously called. */
+void vdo_grow_block_map(struct block_map *map, struct vdo_completion *parent)
+{
+ vdo_schedule_operation(map->action_manager,
+ VDO_ADMIN_STATE_SUSPENDED_OPERATION,
+ grow_forest, NULL, NULL, parent);
+}
+
+void vdo_abandon_block_map_growth(struct block_map *map)
+{
+ struct forest *forest = vdo_forget(map->next_forest);
+
+ if (forest != NULL)
+ deforest(forest, forest->segments - 1);
+
+ map->next_entry_count = 0;
+}
+
+/* Release the page completion and then continue the requester. */
+static inline void finish_processing_page(struct vdo_completion *completion, int result)
+{
+ struct vdo_completion *parent = completion->parent;
+
+ vdo_release_page_completion(completion);
+ vdo_continue_completion(parent, result);
+}
+
+static void handle_page_error(struct vdo_completion *completion)
+{
+ finish_processing_page(completion, completion->result);
+}
+
+/* Fetch the mapping page for a block map update, and call the provided handler when fetched. */
+static void fetch_mapping_page(struct data_vio *data_vio, bool modifiable,
+ vdo_action_fn action)
+{
+ struct block_map_zone *zone = data_vio->logical.zone->block_map_zone;
+
+ if (vdo_is_state_draining(&zone->state)) {
+ continue_data_vio_with_error(data_vio, VDO_SHUTTING_DOWN);
+ return;
+ }
+
+ vdo_get_page(&data_vio->page_completion, zone,
+ data_vio->tree_lock.tree_slots[0].block_map_slot.pbn,
+ modifiable, &data_vio->vio.completion,
+ action, handle_page_error, false);
+}
+
+/**
+ * clear_mapped_location() - Clear a data_vio's mapped block location, setting it to be unmapped.
+ *
+ * This indicates the block map entry for the logical block is either unmapped or corrupted.
+ */
+static void clear_mapped_location(struct data_vio *data_vio)
+{
+ data_vio->mapped = (struct zoned_pbn) {
+ .state = VDO_MAPPING_STATE_UNMAPPED,
+ };
+}
+
+/**
+ * set_mapped_location() - Decode and validate a block map entry, and set the mapped location of a
+ * data_vio.
+ *
+ * Return: VDO_SUCCESS or VDO_BAD_MAPPING if the map entry is invalid or an error code for any
+ * other failure
+ */
+static int __must_check set_mapped_location(struct data_vio *data_vio,
+ const struct block_map_entry *entry)
+{
+ /* Unpack the PBN for logging purposes even if the entry is invalid. */
+ struct data_location mapped = vdo_unpack_block_map_entry(entry);
+
+ if (vdo_is_valid_location(&mapped)) {
+ int result;
+
+ result = vdo_get_physical_zone(vdo_from_data_vio(data_vio),
+ mapped.pbn, &data_vio->mapped.zone);
+ if (result == VDO_SUCCESS) {
+ data_vio->mapped.pbn = mapped.pbn;
+ data_vio->mapped.state = mapped.state;
+ return VDO_SUCCESS;
+ }
+
+ /*
+ * Return all errors not specifically known to be errors from validating the
+ * location.
+ */
+ if ((result != VDO_OUT_OF_RANGE) && (result != VDO_BAD_MAPPING))
+ return result;
+ }
+
+ /*
+ * Log the corruption even if we wind up ignoring it for write VIOs, converting all cases
+ * to VDO_BAD_MAPPING.
+ */
+ vdo_log_error_strerror(VDO_BAD_MAPPING,
+ "PBN %llu with state %u read from the block map was invalid",
+ (unsigned long long) mapped.pbn, mapped.state);
+
+ /*
+ * A read VIO has no option but to report the bad mapping--reading zeros would be hiding
+ * known data loss.
+ */
+ if (!data_vio->write)
+ return VDO_BAD_MAPPING;
+
+ /*
+ * A write VIO only reads this mapping to decref the old block. Treat this as an unmapped
+ * entry rather than fail the write.
+ */
+ clear_mapped_location(data_vio);
+ return VDO_SUCCESS;
+}
+
+/* This callback is registered in vdo_get_mapped_block(). */
+static void get_mapping_from_fetched_page(struct vdo_completion *completion)
+{
+ int result;
+ struct vdo_page_completion *vpc = as_vdo_page_completion(completion);
+ const struct block_map_page *page;
+ const struct block_map_entry *entry;
+ struct data_vio *data_vio = as_data_vio(completion->parent);
+ struct block_map_tree_slot *tree_slot;
+
+ if (completion->result != VDO_SUCCESS) {
+ finish_processing_page(completion, completion->result);
+ return;
+ }
+
+ result = validate_completed_page(vpc, false);
+ if (result != VDO_SUCCESS) {
+ finish_processing_page(completion, result);
+ return;
+ }
+
+ page = (const struct block_map_page *) get_page_buffer(vpc->info);
+ tree_slot = &data_vio->tree_lock.tree_slots[0];
+ entry = &page->entries[tree_slot->block_map_slot.slot];
+
+ result = set_mapped_location(data_vio, entry);
+ finish_processing_page(completion, result);
+}
+
+void vdo_update_block_map_page(struct block_map_page *page, struct data_vio *data_vio,
+ physical_block_number_t pbn,
+ enum block_mapping_state mapping_state,
+ sequence_number_t *recovery_lock)
+{
+ struct block_map_zone *zone = data_vio->logical.zone->block_map_zone;
+ struct block_map *block_map = zone->block_map;
+ struct recovery_journal *journal = block_map->journal;
+ sequence_number_t old_locked, new_locked;
+ struct tree_lock *tree_lock = &data_vio->tree_lock;
+
+ /* Encode the new mapping. */
+ page->entries[tree_lock->tree_slots[tree_lock->height].block_map_slot.slot] =
+ vdo_pack_block_map_entry(pbn, mapping_state);
+
+ /* Adjust references on the recovery journal blocks. */
+ old_locked = *recovery_lock;
+ new_locked = data_vio->recovery_sequence_number;
+
+ if ((old_locked == 0) || (old_locked > new_locked)) {
+ vdo_acquire_recovery_journal_block_reference(journal, new_locked,
+ VDO_ZONE_TYPE_LOGICAL,
+ zone->zone_number);
+
+ if (old_locked > 0) {
+ vdo_release_recovery_journal_block_reference(journal, old_locked,
+ VDO_ZONE_TYPE_LOGICAL,
+ zone->zone_number);
+ }
+
+ *recovery_lock = new_locked;
+ }
+
+ /*
+ * FIXME: explain this more
+ * Release the transferred lock from the data_vio.
+ */
+ vdo_release_journal_entry_lock(journal, new_locked);
+ data_vio->recovery_sequence_number = 0;
+}
+
+static void put_mapping_in_fetched_page(struct vdo_completion *completion)
+{
+ struct data_vio *data_vio = as_data_vio(completion->parent);
+ sequence_number_t old_lock;
+ struct vdo_page_completion *vpc;
+ struct page_info *info;
+ int result;
+
+ if (completion->result != VDO_SUCCESS) {
+ finish_processing_page(completion, completion->result);
+ return;
+ }
+
+ vpc = as_vdo_page_completion(completion);
+ result = validate_completed_page(vpc, true);
+ if (result != VDO_SUCCESS) {
+ finish_processing_page(completion, result);
+ return;
+ }
+
+ info = vpc->info;
+ old_lock = info->recovery_lock;
+ vdo_update_block_map_page((struct block_map_page *) get_page_buffer(info),
+ data_vio, data_vio->new_mapped.pbn,
+ data_vio->new_mapped.state, &info->recovery_lock);
+ set_info_state(info, PS_DIRTY);
+ add_to_dirty_lists(info->cache->zone, &info->state_entry,
+ VDO_CACHE_PAGE, old_lock, info->recovery_lock);
+ finish_processing_page(completion, VDO_SUCCESS);
+}
+
+/* Read a stored block mapping into a data_vio. */
+void vdo_get_mapped_block(struct data_vio *data_vio)
+{
+ if (data_vio->tree_lock.tree_slots[0].block_map_slot.pbn == VDO_ZERO_BLOCK) {
+ /*
+ * We know that the block map page for this LBN has not been allocated, so the
+ * block must be unmapped.
+ */
+ clear_mapped_location(data_vio);
+ continue_data_vio(data_vio);
+ return;
+ }
+
+ fetch_mapping_page(data_vio, false, get_mapping_from_fetched_page);
+}
+
+/* Update a stored block mapping to reflect a data_vio's new mapping. */
+void vdo_put_mapped_block(struct data_vio *data_vio)
+{
+ fetch_mapping_page(data_vio, true, put_mapping_in_fetched_page);
+}
+
+struct block_map_statistics vdo_get_block_map_statistics(struct block_map *map)
+{
+ zone_count_t zone = 0;
+ struct block_map_statistics totals;
+
+ memset(&totals, 0, sizeof(struct block_map_statistics));
+ for (zone = 0; zone < map->zone_count; zone++) {
+ const struct block_map_statistics *stats =
+ &(map->zones[zone].page_cache.stats);
+
+ totals.dirty_pages += READ_ONCE(stats->dirty_pages);
+ totals.clean_pages += READ_ONCE(stats->clean_pages);
+ totals.free_pages += READ_ONCE(stats->free_pages);
+ totals.failed_pages += READ_ONCE(stats->failed_pages);
+ totals.incoming_pages += READ_ONCE(stats->incoming_pages);
+ totals.outgoing_pages += READ_ONCE(stats->outgoing_pages);
+ totals.cache_pressure += READ_ONCE(stats->cache_pressure);
+ totals.read_count += READ_ONCE(stats->read_count);
+ totals.write_count += READ_ONCE(stats->write_count);
+ totals.failed_reads += READ_ONCE(stats->failed_reads);
+ totals.failed_writes += READ_ONCE(stats->failed_writes);
+ totals.reclaimed += READ_ONCE(stats->reclaimed);
+ totals.read_outgoing += READ_ONCE(stats->read_outgoing);
+ totals.found_in_cache += READ_ONCE(stats->found_in_cache);
+ totals.discard_required += READ_ONCE(stats->discard_required);
+ totals.wait_for_page += READ_ONCE(stats->wait_for_page);
+ totals.fetch_required += READ_ONCE(stats->fetch_required);
+ totals.pages_loaded += READ_ONCE(stats->pages_loaded);
+ totals.pages_saved += READ_ONCE(stats->pages_saved);
+ totals.flush_count += READ_ONCE(stats->flush_count);
+ }
+
+ return totals;
+}